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  • (iphone) maintaining CGContextRef or CGLayerRef is a bad idea?

    - by Eugene
    Hi, I need to work with many images, and I can't hold them as UIImage in memory because they are too big. I also need to change colors of image and merge them on the fly. Creating UIImage from underlying NSData, change color, and combine them when you can't have many images on memory is fairly slow. (as far as I can get) I thought maybe I can store underlying CGLayerRef(for image that will be combined) and CGContextRef(the resulting combined image). I am new to drawing world, and not sure if CGLayerRef or CGContextRef is smaller in memory than UIImage. I recently heard that w*h image takes up w*h*4 bytes in memory. Does CGLayerRef or CGContextRef also take up that much memory? Thank you

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  • Boost Shared Pointer: Simultaneous Read Access Across Multiple Threads

    - by Nikhil
    I have a thread A which allocates memory and assigns it to a shared pointer. Then this thread spawns 3 other threads X, Y and Z and passes a copy of the shared pointer to each. When X, Y and Z go out of scope, the memory is freed. But is there a possibility that 2 threads X, Y go out of scope at the exact same point in time and there is a race condition on reference count so instead of decrementing it by 2, it only gets decremented once. So, now the reference count newer drops to 0, so there is a memory leak. Note that, X, Y and Z are only reading the memory. Not writing or resetting the shared pointer. To cut a long story short, can there be a race condition on the reference count and can that lead to memory leaks?

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  • Realtek RTL8111/8168B wired network doesn't work anymore

    - by Radar4002
    This sounds like it's a common problem upgrading 11.04, but I am having trouble finding a common solution, and one that will work for me. I just applied updates via the update manager and now my wired network connection is down. I know Ubuntu network settings is the issue, because I have a dual-boot with Win 7 and my network/internet is fine on Win 7. I don't know too much about networking, so what can I do to trouble shoot this issue? I can choose an older grub version, 2.6.38-8 instead of 2.6.38-11 and this does not resolve the issue. Here is my lspci result: 00:00.0 Host bridge: ATI Technologies Inc RD890 Northbridge only single slot PCI-e GFX Hydra part (rev 02) 00:02.0 PCI bridge: ATI Technologies Inc RD890 PCI to PCI bridge (PCI express gpp port B) 00:04.0 PCI bridge: ATI Technologies Inc RD890 PCI to PCI bridge (PCI express gpp port D) 00:05.0 PCI bridge: ATI Technologies Inc RD890 PCI to PCI bridge (PCI express gpp port E) 00:06.0 PCI bridge: ATI Technologies Inc RD890 PCI to PCI bridge (PCI express gpp port F) 00:07.0 PCI bridge: ATI Technologies Inc RD890 PCI to PCI bridge (PCI express gpp port G) 00:09.0 PCI bridge: ATI Technologies Inc RD890 PCI to PCI bridge (PCI express gpp port H) 00:0a.0 PCI bridge: ATI Technologies Inc RD890 PCI to PCI bridge (external gfx1 port A) 00:11.0 SATA controller: ATI Technologies Inc SB7x0/SB8x0/SB9x0 SATA Controller [IDE mode] (rev 40) 00:12.0 USB Controller: ATI Technologies Inc SB7x0/SB8x0/SB9x0 USB OHCI0 Controller 00:12.2 USB Controller: ATI Technologies Inc SB7x0/SB8x0/SB9x0 USB EHCI Controller 00:13.0 USB Controller: ATI Technologies Inc SB7x0/SB8x0/SB9x0 USB OHCI0 Controller 00:13.2 USB Controller: ATI Technologies Inc SB7x0/SB8x0/SB9x0 USB EHCI Controller 00:14.0 SMBus: ATI Technologies Inc SBx00 SMBus Controller (rev 41) 00:14.1 IDE interface: ATI Technologies Inc SB7x0/SB8x0/SB9x0 IDE Controller (rev 40) 00:14.2 Audio device: ATI Technologies Inc SBx00 Azalia (Intel HDA) (rev 40) 00:14.3 ISA bridge: ATI Technologies Inc SB7x0/SB8x0/SB9x0 LPC host controller (rev 40) 00:14.4 PCI bridge: ATI Technologies Inc SBx00 PCI to PCI Bridge (rev 40) 00:14.5 USB Controller: ATI Technologies Inc SB7x0/SB8x0/SB9x0 USB OHCI2 Controller 00:15.0 PCI bridge: ATI Technologies Inc Device 43a0 00:16.0 USB Controller: ATI Technologies Inc SB7x0/SB8x0/SB9x0 USB OHCI0 Controller 00:16.2 USB Controller: ATI Technologies Inc SB7x0/SB8x0/SB9x0 USB EHCI Controller 00:18.0 Host bridge: Advanced Micro Devices [AMD] Family 10h Processor HyperTransport Configuration 00:18.1 Host bridge: Advanced Micro Devices [AMD] Family 10h Processor Address Map 00:18.2 Host bridge: Advanced Micro Devices [AMD] Family 10h Processor DRAM Controller 00:18.3 Host bridge: Advanced Micro Devices [AMD] Family 10h Processor Miscellaneous Control 00:18.4 Host bridge: Advanced Micro Devices [AMD] Family 10h Processor Link Control 01:00.0 VGA compatible controller: ATI Technologies Inc Juniper [Radeon HD 5700 Series] 01:00.1 Audio device: ATI Technologies Inc Juniper HDMI Audio [Radeon HD 5700 Series] 02:00.0 USB Controller: NEC Corporation uPD720200 USB 3.0 Host Controller (rev 03) 05:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI Express Gigabit Ethernet controller (rev 03) 06:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI Express Gigabit Ethernet controller (rev 03) 07:00.0 SATA controller: JMicron Technology Corp. JMB362/JMB363 Serial ATA Controller (rev 03) 07:00.1 IDE interface: JMicron Technology Corp. JMB362/JMB363 Serial ATA Controller (rev 03) 08:0e.0 FireWire (IEEE 1394): Texas Instruments TSB43AB23 IEEE-1394a-2000 Controller (PHY/Link) 09:00.0 SATA controller: JMicron Technology Corp. JMB362/JMB363 Serial ATA Controller (rev 02) 09:00.1 IDE interface: JMicron Technology Corp. JMB362/JMB363 Serial ATA Controller (rev 02) Here is my sudo lshw -class network: *-network description: Ethernet interface product: RTL8111/8168B PCI Express Gigabit Ethernet controller vendor: Realtek Semiconductor Co., Ltd. physical id: 0 bus info: pci@0000:05:00.0 logical name: eth0 version: 03 serial: 6c:f0:49:e7:72:e8 size: 10Mbit/s capacity: 1Gbit/s width: 64 bits clock: 33MHz capabilities: pm msi pciexpress msix vpd bus_master cap_list rom ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation configuration: autonegotiation=on broadcast=yes driver=r8169 driverversion=2.3LK-NAPI duplex=half latency=0 link=no multicast=yes port=MII speed=10Mbit/s resources: irq:40 ioport:9e00(size=256) memory:fceff000-fcefffff memory:fcef8000-fcefbfff memory:fce00000-fce1ffff *-network description: Ethernet interface product: RTL8111/8168B PCI Express Gigabit Ethernet controller vendor: Realtek Semiconductor Co., Ltd. physical id: 0 bus info: pci@0000:06:00.0 logical name: eth1 version: 03 serial: 6c:f0:49:e7:72:ea size: 10Mbit/s capacity: 1Gbit/s width: 64 bits clock: 33MHz capabilities: pm msi pciexpress msix vpd bus_master cap_list rom ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation configuration: autonegotiation=on broadcast=yes driver=r8169 driverversion=2.3LK-NAPI duplex=half latency=0 link=no multicast=yes port=MII speed=10Mbit/s resources: irq:47 ioport:8e00(size=256) memory:fddff000-fddfffff memory:fddf8000-fddfbfff memory:fdd00000-fdd1ffff

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  • Exalytics and Oracle Business Intelligence Enterprise Edition (OBIEE) Partner Workshop

    - by mseika
    Workshop Description Oracle Fusion Middleware 11g is the #1 application infrastructure foundation. It enables enterprises to create and run agile and intelligent business applications and maximize IT efficiency by exploiting modern hardware and software architectures. Oracle Exalytics Business Intelligence Machine is the world’s first engineered system specifically designed to deliver high performance analysis, modeling and planning. Built using industry-standard hardware, market-leading business intelligence software and in-memory database technology, Oracle Exalytics is an optimized system that delivers unmatched speed, visualizations and scalability for Business Intelligence and Enterprise Performance Management applications. This FREE hands-on, partner workshop highlights both the hardware and software components that are engineered to work together to deliver Oracle Exalytics - an optimized version of the industry-leading Oracle TimesTen In-Memory Database with analytic extensions, a highly scalable Oracle server designed specifically for in-memory business intelligence, and Oracle’s proven Business Intelligence Foundation with enhanced visualization capabilities and performance optimizations. This workshop will provide hands-on experience with Oracle's latest engineered system. Topics covered will include TimesTen In-Memory Database and the new Summary Advisor for Exalytics, the technical details (including mobile features) of the latest release of visualization enhancements for OBI-EE, and technical updates on Essbase. After taking this course, you will be well prepared to architect, build, demo, and implement an end-to-end Exalytics solution. You will also be able to extend your current analytical and enterprise performance management application implementations with numerous Oracle technologies specifically enhanced to take advantage of the compute capacity and in-memory capabilities of Oracle Exalytics.If you are a BI or Data Warehouse Architect, developer or consultant, you don’t want to miss this 3-day workshop. Register Now! Presentations Exalytics Architectural Overview Upgrade and Lifecycle Management Times Ten for Exalytics Summary Advisor Utility Essbase and EPM System on Exalytics Dashboard and Analysis Interactions OBIEE 11.1.1.6 Features and Advanced Topics Lab OutlineThe labs showcase Oracle Exalytics core components and functionality and provide expertise of Oracle Business Intelligence 11.1.1.6 new features and updates from prior releases. The hands-on activities are based on an Oracle VirtualBox image with software and training samples pre-installed. Lab Environment Setup Creating and Working with Oracle TimesTen In-Memory Database Running Summary Advisor Utility Working with Exalytics Visualization Features – Dashboard and Analysis Interactions Audience Oracle Partners BI and EPM Application Developers and Implementers System Integrators and Solution Consultants Data Warehouse Developers Enterprise Architects Prerequisites Experience and understanding of OBIEE 11g is required Previous attendance of Oracle Business Intelligence Foundation Suite Workshop or BIEE 11gIntroduction Workshop is highly recommended Good understanding of data warehousing and data modeling for reporting and analysis purpose Strong experience with database technologies preferred Equipment RequirementsThis workshop requires attendees to provide their own laptops for this class.Attendee laptops must meet the following minimum hardware/software requirements: Hardware Minimum 8GB RAM 60 GB free space (includes staging) USB 2.0 port (at least one available) It is strongly recommended that you bring a mouse. You will be working in a development environment and using the mouse heavily. Software One of the following operating systems: 64-bit Windows host/laptop OS 64-bit host/laptop OS with a Windows VM (XP, Server, or Win 7, BIC2g, etc.) Internet Explorer 7.x/8.x or Firefox 3.5.x WINRAR or 7ziputility to unzip workshop files: Download-able from http://www.win-rar.com/download.html Download-able from http://www.7zip.com/ Oracle VirtualBox 4.0.2 or higher Downloadable from http://www.virtualbox.org/wiki/Downloads CPU virtualization mode needs to be enabled. We will provide guidance on the day of the workshop. Attendees will be given a VirtualBox image containing a pre-installed Oracle Exalytics environment. Schedule This workshop is 3 days. - Times vary by country!9:00am: Sign-in and technical setup 9:30am: Workshop starts 5:00pm: Workshop ends Oracle Exalytics and Business Intelligence (OBIEE) Workshop December 11-13, 2012: Oracle BVP, Birmingham, UK Register Here. Questions? Send email to: [email protected] Oracle Platform Technologies Enablement Services

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  • Spring scheduler shutdown error

    - by Alex
    During development a SPRING based scheduler in a tomcat container, I always get this logoutput at undeploy webapp or shutdown server: Apr 28, 2010 4:21:33 PM org.apache.catalina.core.StandardService stop INFO: Stopping service Catalina Apr 28, 2010 4:21:33 PM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads SEVERE: A web application appears to have started a thread named [org.springframework.scheduling.quartz.SchedulerFactoryBean#0_Worker-1] but has failed to stop it. This is very likely to create a memory leak. Apr 28, 2010 4:21:33 PM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads SEVERE: A web application appears to have started a thread named [org.springframework.scheduling.quartz.SchedulerFactoryBean#0_Worker-2] but has failed to stop it. This is very likely to create a memory leak. Apr 28, 2010 4:21:33 PM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads SEVERE: A web application appears to have started a thread named [org.springframework.scheduling.quartz.SchedulerFactoryBean#0_Worker-3] but has failed to stop it. This is very likely to create a memory leak. Apr 28, 2010 4:21:33 PM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads SEVERE: A web application appears to have started a thread named [org.springframework.scheduling.quartz.SchedulerFactoryBean#0_Worker-4] but has failed to stop it. This is very likely to create a memory leak. Apr 28, 2010 4:21:33 PM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads SEVERE: A web application appears to have started a thread named [org.springframework.scheduling.quartz.SchedulerFactoryBean#0_Worker-5] but has failed to stop it. This is very likely to create a memory leak. . . . SEVERE: A web application created a ThreadLocal with key of type [org.springframework.core.NamedThreadLocal] (value [Prototype beans currently in creation]) and a value of type [null] (value [null]) but failed to remove it when the web application was stopped. To prevent a memory leak, the ThreadLocal has been forcibly removed. Apr 28, 2010 4:21:34 PM org.apache.coyote.http11.Http11Protocol destroy INFO: Stopping Coyote HTTP/1.1 on http-8606 How can I fix this?

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  • How to mmap the stack for the clone() system call on linux?

    - by Joseph Garvin
    The clone() system call on Linux takes a parameter pointing to the stack for the new created thread to use. The obvious way to do this is to simply malloc some space and pass that, but then you have to be sure you've malloc'd as much stack space as that thread will ever use (hard to predict). I remembered that when using pthreads I didn't have to do this, so I was curious what it did instead. I came across this site which explains, "The best solution, used by the Linux pthreads implementation, is to use mmap to allocate memory, with flags specifying a region of memory which is allocated as it is used. This way, memory is allocated for the stack as it is needed, and a segmentation violation will occur if the system is unable to allocate additional memory." The only context I've ever heard mmap used in is for mapping files into memory, and indeed reading the mmap man page it takes a file descriptor. How can this be used for allocating a stack of dynamic length to give to clone()? Is that site just crazy? ;) In either case, doesn't the kernel need to know how to find a free bunch of memory for a new stack anyway, since that's something it has to do all the time as the user launches new processes? Why does a stack pointer even need to be specified in the first place if the kernel can already figure this out?

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  • Why are virtual methods considered early bound?

    - by AspOnMyNet
    One definition of binding is that it is the act of replacing function names with memory addresses. a) Thus I assume early binding means function calls are replaced with memory addresses during compilation process, while with late binding this replacement happens during runtime? b) Why are virtual methods also considered early bound (thus the target method is found at compile time, and code is created that will call this method)? As far as I know, with virtual methods the call to actual method is resolved only during runtime and not compile time?! thanx EDIT: 1) A a=new A(); a.M(); As far as I know, it is not known at compile time where on the heap (thus at which memory address ) will instance a be created during runtime. Now, with early binding the function calls are replaced with memory addresses during compilation process. But how can compiler replace function call with memory address, if it doesn’t know where on the heap will object a be created during runtime ( here I’m assuming the address of method a.M will also be at same memory location as a )? 2) v-table calls are neither early nor late bound. Instead there's an offset into a table of function pointers. The offset is fixed at compile time, but which table the function pointer is chosen from depends on the runtime type of the object (the object contains a hidden pointer to its v-table), so the final function address is found at runtime. But assuming the object of type T is created via reflection ( thus app doesn’t even know of existence of type T ), then how can at compile time exist an entry point for that type of object?

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  • How to declare a 2D array of 2D array pointers and access them?

    - by vikramtheone
    Hi Guys, How can I declare an 2D array of 2D Pointers? And later access the individual array elements of the 2D arrays. Is my approach correct? void alloc_2D(int ***memory, unsigned int rows, unsigned int cols); int main() { int i, j; int **ptr; int **array[10][10]; for(i=0;i<10;i++) { for(j=0;j<10;j++) { alloc_2D(&ptr, 10, 10); array[i][j] = ptr; } } //After I do this, how can I access the 10 individual 2D arrays? return 0; } void alloc_2D(int ***memory, unsigned int rows, unsigned int cols) { int **ptr; *memory = NULL; ptr = malloc(rows * sizeof(int*)); if(ptr == NULL) { printf("\nERROR: Memory allocation failed!"); } else { int i; for(i = 0; i< rows; i++) { ptr[i] = malloc(cols * sizeof(float)); if(ptr[i]==NULL) { printf("\nERROR: Memory allocation failed!"); } } } *memory = ptr; }

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  • Noob - Cycle through stored names and skip blanks

    - by ActiveJimBob
    NOOB trying to make my code more efficient. On scroll button push, the function 'SetName' stores a number to integer 'iName' which is index against 5 names stored in memory. If a name is not set in memeory, it skips to the next. The code works, but takes up a lot of room. Any advice appreciated. Code: #include <string.h> int iName = 0; int iNewName = 0; BYTE GetName () { return iName; } void SetName (int iNewName) { while (iName != iNewName) { switch (byNewName) { case 1: if (strlen (memory.m_nameA) == 0) new_name++; else iName = iNewName; break; case 2: if (strlen (memory.m_nameB) == 0) new_name++; else iName = iNewName; break; case 3: if (strlen (memory.m_nameC) == 0) new_name++; else iName = iNewName; break; case 4: if (strlen (memory.m_nameD) == 0) new_name++; else iName = iNewName; break; case 5: if (strlen (memory.m_nameE) == 0) new_name++; else iName = iNewName; break; default: iNewName = 1; break; } // end of case } // end of loop } // end of SetName function void main () { while(1) { if (Button_pushed) SetName(GetName+1); } // end of infinite loop } // end of main

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  • Recommendations for IPC between parent and child processes in .NET?

    - by Jeremy
    My .NET program needs to run an algorithm that makes heavy use of 3rd party libraries (32-bit), most of which are unmanaged code. I want to drive the CPU as hard as I can, so the code runs several threads in parallel to divide up the work. I find that running all these threads simultaneously results in temporary memory spikes, causing the process' virtual memory size to approach the 2 GB limit. This memory is released back pretty quickly, but occasionally if enough threads enter the wrong sections of code at once, the process crosses the "red line" and either the unmanaged code or the .NET code encounters an out of memory error. I can throttle back the number of threads but then my CPU usage is not as high as I would like. I am thinking of creating worker processes rather than worker threads to help avoid the out of memory errors, since doing so would give each thread of execution its own 2 GB of virtual address space (my box has lots of RAM). I am wondering what are the best/easiest methods to communicate the input and output between the processes in .NET? The file system is an obvious choice. I am used to shared memory, named pipes, and such from my UNIX background. Is there a Windows or .NET specific mechanism I should use?

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  • Reading and writing in parallel

    - by Malfist
    I want to be able to read and write a large file in parallel, or if not in parallel, at least in blocks so that I don't use up so much memory. This is my current code: // Define memory stream which will be used to hold encrypted data. MemoryStream memoryStream = new MemoryStream(); // Define cryptographic stream (always use Write mode for encryption). CryptoStream cryptoStream = new CryptoStream(memoryStream, encryptor, CryptoStreamMode.Write); //start encrypting using (BinaryReader reader = new BinaryReader(File.Open(fileIn, FileMode.Open))) { byte[] buffer = new byte[1024 * 1024]; int read = 0; do { read = reader.Read(buffer, 0, buffer.Length); cryptoStream.Write(buffer, 0, read); } while (read == buffer.Length); } // Finish encrypting. cryptoStream.FlushFinalBlock(); // Convert our encrypted data from a memory stream into a byte array. //byte[] cipherTextBytes = memoryStream.ToArray(); //write our memory stream to a file memoryStream.Position = 0; using (BinaryWriter writer = new BinaryWriter(File.Open(fileOut, FileMode.Create))) { byte[] buffer = new byte[1024 * 1024]; int read = 0; do { read = memoryStream.Read(buffer, 0, buffer.Length); writer.Write(buffer, 0, read); } while (read == buffer.Length); } // Close both streams. memoryStream.Close(); cryptoStream.Close(); As you can see, it reads the entire file into memory, encrypts it, then writes it out. If I happen to be encrypting files that are very large (2GB+) it tends not to work, or at the very least, consumes ~97% of my memory. How could I do it in a more effective manner?

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  • unbuffered I/O in Linux

    - by stuck
    I'm writing lots and lots of data that will not be read again for weeks - as my program runs the amount of free memory on the machine (displayed with 'free' or 'top') drops very quickly, the amount of memory my app uses does not increase - neither does the amount of memory used by other processes. This leads me to believe the memory is being consumed by the filesystems cache - since I do not intend to read this data for a long time I'm hoping to bypass the systems buffers, such that my data is written directly to disk. I dont have dreams of improving perf or being a super ninja, my hope is to give a hint to the filesystem that I'm not going to be coming back for this memory any time soon, so dont spend time optimizing for those cases. On Windows I've faced similar problems and fixed the problem using FILE_FLAG_NO_BUFFERING|FILE_FLAG_WRITE_THROUGH - the machines memory was not consumed by my app and the machine was more usable in general. I'm hoping to duplicate the improvements I've seen but on Linux. On Windows there is the restriction of writing in sector sized pieces, I'm happy with this restriction for the amount of gain I've measured. is there a similar way to do this in Linux?

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  • What are some ways to accomplish a dynamic array?

    - by Ted
    I'm going to start working on a new game and one of the things I'd like to accomplish is a dynamic array sort of system that would hold map data. The game will be top-down 2d and made with XNA 4.0 and C#. You will begin in a randomized area which will essentially be tile based. As such a 2 dimensional array would be one way to accomplish this by holding numerical values which would correspond to a list of textures and that would be how it would draw this randomly created map. The problem is I would kind of only like to create the area around where you start and they could venture in which ever direction they wanted to. This would mean I'd have to populate the map array with more randomized data in the direction they go. I could make a really large array and use the center of it and the rest would be in anticipation of new content to be made, but that just seems very inefficient. I suppose when they start a new game I could have a one time map creation process that would go through and create a large randomly generated map array, but holding all of in memory at all times seems also inefficient. Perhaps if there was a way that I'd only hold parts of that map data in memory at one time and somehow not hold the rest in memory. In the end I only need to have a chunk of the map somewhat close to them in memory so perhaps some of you might have suggestions on good ways to approach this kind of randomized map and dynamic array problem. It wouldn't need to be a dynamic array type of thing if I made it so that it pulled in map data nearby that is needed and then once off the screen and not needed it could somehow get rid of that memory that way I wouldn't have a huge array taking up a bunch of memory.

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  • An increase to 3 Gig of RAM slows down Ubuntu 10.04 LTS

    - by williepabon
    I have Ubuntu 10.04 running from an external hard drive (installed on an enclosure) connected via USB port. Like a month or so ago, I increased RAM on my pc from 2 Gigs to 3 Gigs. This resulted on extremely long boot times and slow application loads. While I was understanding the nature of my problem, I posted various threads on this forum ( Questions # 188417, 188801), where I was advised to gather speed tests, and other info on my machine. I was also suggested that I might have problems with the RAM installed. Initially, I did not consider that possibility because: 1) I did a memory test with a diagnostic program from DELL (My pc is from Dell) 2) My pc works fine with Windows XP (the default OS), no problems with memory 3) My pc works fine when booting with Ubuntu 10.10 memory stick, no speed problems 4) My pc works fine when booting with Ubuntu 11.10 memory stick, no speed problems Anyway, I performed the memory tests suggested. But before doing it, and to check out any possibility of hardware issues on the hard drive, I did the following: (1) purchased a new hard drive enclosure and moved my hard drive to it, (2) purchased a new USB cable and used it to connect my hard drive/enclosure setup to a different USB port on my pc. Then, I performed speed tests with 1 Gig, 2 Gigs and 3 Gigs of RAM with my Ubuntu 10.04 OS. Ubuntu 10.04 worked well when booted with 1 Gig or 2 Gigs of RAM. When I increased to 3 Gigs, it slowed down to a crawl. I can't understand the relationship between an increase of 1 Gig and the effect it has in Ubuntu 10.04. This doesn't happen with Ubuntu 10.10 and 11.10. Unfortunately for me, Ubuntu 10.04 is my principal work operating system. So, I need a solution for this. Hardware and system information: DELL Precision 670 2 internal SATA Hard drives Audigy 2 ZS audio system Factory OS: Windows XP Professional SP3 NVidia 8400 GTS video card More info: williepabon@WP-WrkStation:~$ uname -a Linux WP-WrkStation 2.6.32-38-generic #83-Ubuntu SMP Wed Jan 4 11:13:04 UTC 2012 i686 GNU/Linux williepabon@WP-WrkStation:~$ lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 10.04.4 LTS Release: 10.04 Codename: lucid Speed test with the 3 Gigs of RAM installed: williepabon@WP-WrkStation:~$ sudo hdparm -tT /dev/sdc [sudo] password for williepabon: /dev/sdc: Timing cached reads: 84 MB in 2.00 seconds = 41.96 MB/sec Timing buffered disk reads: 4 MB in 3.81 seconds = 1.05 MB/sec This is a very slow transfer rate from a hard drive. I will really appreciate a solution or a work around for this problem. I know that that there are users that have Ubuntu 10.04 with 3 Gigs or more of RAM and they don't have this problem. Same question asked on Launchpad for reference.

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  • How does I/O work for large graph databases?

    - by tjb1982
    I should preface this by saying that I'm mostly a front end web developer, trained as a musician, but over the past few years I've been getting more and more into computer science. So one idea I have as a fun toy project to learn about data structures and C programming was to design and implement my own very simple database that would manage an adjacency list of posts. I don't want SQL (maybe I'll do my own query language? I'm just having fun). It should support ACID. It should be capable of storing 1TB let's say. So with that, I was trying to think of how a database even stores data, without regard to data structures necessarily. I'm working on linux, and I've read that in that world "everything is a file," including hardware (like /dev/*), so I think that that obviously has to apply to a database, too, and it clearly does--whether it's MySQL or PostgreSQL or Neo4j, the database itself is a collection of files you can see in the filesystem. That said, there would come a point in scale where loading the entire database into primary memory just wouldn't work, so it doesn't make sense to design it with that mindset (I assume). However, reading from secondary memory would be much slower and regardless some portion of the database has to be in primary memory in order for you to be able to do anything with it. I read this post: Why use a database instead of just saving your data to disk? And I found it difficult to understand how other databases, like SQLite or Neo4j, read and write from secondary memory and are still very fast (faster, it would seem, than simply writing files to the filesystem as the above question suggests). It seems the key is indexing. But even indexes need to be stored in secondary memory. They are inherently smaller than the database itself, but indexes in a very large database might be prohibitively large, too. So my question is how is I/O generally done with large databases like the one I described above that would be at least 1TB storing a big adjacency list? If indexing is more or less the answer, how exactly does indexing work--what data structures should be involved?

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  • Does Ubuntu Touch consume less than Android?

    - by Eduard Florinescu
    One of the problems of new OSs is power consumption. That is because power and performance requires a lot of tweaks and experience with the kernel, drivers and OS code-base on one hand, and a lot of extensive long-term test and quality assurance on the other hand. Given that Android is a rather old and established OS I saw that it has pretty good power consumption. Phoronix does this kind of comparissions but I was not able to find to much about Ubuntu Touch. Does Ubuntu Touch consume less than Android in general, do you have data on some platforms compared?

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  • Subterranean IL: Volatile

    - by Simon Cooper
    This time, we'll be having a look at the volatile. prefix instruction, and one of the differences between volatile in IL and C#. The volatile. prefix volatile is a tricky one, as there's varying levels of documentation on it. From what I can see, it has two effects: It prevents caching of the load or store value; rather than reading or writing to a cached version of the memory location (say, the processor register or cache), it forces the value to be loaded or stored at the 'actual' memory location, so it is then immediately visible to other threads. It forces a memory barrier at the prefixed instruction. This ensures instructions don't get re-ordered around the volatile instruction. This is slightly more complicated than it first seems, and only seems to matter on certain architectures. For more details, Joe Duffy has a blog post going into the details. For this post, I'll be concentrating on the first aspect of volatile. Caching field accesses To demonstrate this, I created a simple multithreaded IL program. It boils down to the following code: .class public Holder { .field public static class Holder holder .field public bool stop .method public static specialname void .cctor() { newobj instance void Holder::.ctor() stsfld class Holder Holder::holder ret }}.method private static void Main() { .entrypoint // Thread t = new Thread(new ThreadStart(DoWork)) // t.Start() // Thread.Sleep(2000) // Console.WriteLine("Stopping thread...") ldsfld class Holder Holder::holder ldc.i4.1 stfld bool Holder::stop call instance void [mscorlib]System.Threading.Thread::Join() ret}.method private static void DoWork() { ldsfld class Holder Holder::holder // while (!Holder.holder.stop) {} DoWork: dup ldfld bool Holder::stop brfalse DoWork pop ret} If you compile and run this code, you'll find that the call to Thread.Join() never returns - the DoWork spinlock is reading a cached version of Holder.stop, which is never being updated with the new value set by the Main method. Adding volatile to the ldfld fixes this: dupvolatile.ldfld bool Holder::stopbrfalse DoWork The volatile ldfld forces the field access to read direct from heap memory, which is then updated by the main thread, rather than using a cached copy. volatile in C# This highlights one of the differences between IL and C#. In IL, volatile only applies to the prefixed instruction, whereas in C#, volatile is specified on a field to indicate that all accesses to that field should be volatile (interestingly, there's no mention of the 'no caching' aspect of volatile in the C# spec; it only focuses on the memory barrier aspect). Furthermore, this information needs to be stored within the assembly somehow, as such a field might be accessed directly from outside the assembly, but there's no concept of a 'volatile field' in IL! How this information is stored with the field will be the subject of my next post.

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  • Map and fill texture using PBO (OpenGL 3.3)

    - by NtscCobalt
    I'm learning OpenGL 3.3 trying to do the following (as it is done in D3D)... Create Texture of Width, Height, Pixel Format Map texture memory Loop write pixels Unmap texture memory Set Texture Render Right now though it renders as if the entire texture is black. I can't find a reliable source for information on how to do this though. Almost every tutorial I've found just uses glTexSubImage2D and passes a pointer to memory. Here is basically what my code does... (In this case it is generating an 1-byte Alpha Only texture but it is rendering it as the red channel for debugging) GLuint pixelBufferID; glGenBuffers(1, &pixelBufferID); glBindBuffer(GL_PIXEL_UNPACK_BUFFER, pixelBufferID); glBufferData(GL_PIXEL_UNPACK_BUFFER, 512 * 512 * 1, nullptr, GL_STREAM_DRAW); glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0); GLuint textureID; glGenTextures(1, &textureID); glBindTexture(GL_TEXTURE_2D, textureID); glTexImage2D(GL_TEXTURE_2D, 0, GL_R8, 512, 512, 0, GL_RED, GL_UNSIGNED_BYTE, nullptr); glBindTexture(GL_TEXTURE_2D, 0); glBindTexture(GL_TEXTURE_2D, textureID); glBindBuffer(GL_PIXEL_UNPACK_BUFFER, pixelBufferID); void *Memory = glMapBuffer(GL_PIXEL_UNPACK_BUFFER, GL_WRITE_ONLY); // Memory copied here, I know this is valid because it is the same loop as in my working D3D version glUnmapBuffer(GL_PIXEL_UNPACK_BUFFER); glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0); And then here is the render loop. // This chunk left in for completeness glUseProgram(glProgramId); glBindVertexArray(glVertexArrayId); glBindBuffer(GL_ARRAY_BUFFER, glVertexBufferId); glEnableVertexAttribArray(0); glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 20, 0); glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 20, 12); GLuint transformLocationID = glGetUniformLocation(3, 'transform'); glUniformMatrix4fv(transformLocationID , 1, true, somematrix) // Not sure if this is all I need to do glBindTexture(GL_TEXTURE_2D, pTex->glTextureId); GLuint textureLocationID = glGetUniformLocation(glProgramId, "texture"); glUniform1i(textureLocationID, 0); glDrawArrays(GL_TRIANGLES, Offset*3, Triangles*3); Vertex Shader #version 330 core in vec3 Position; in vec2 TexCoords; out vec2 TexOut; uniform mat4 transform; void main() { TexOut = TexCoords; gl_Position = vec4(Position, 1.0) * transform; } Pixel Shader #version 330 core uniform sampler2D texture; in vec2 TexCoords; out vec4 fragColor; void main() { // Output color fragColor.r = texture2D(texture, TexCoords).r; fragColor.g = 0.0f; fragColor.b = 0.0f; fragColor.a = 1.0; }

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  • Does Ubuntu Touch consume less power than Android?

    - by Eduard Florinescu
    One of the problems of new OSs is power consumption. That is because power and performance requires a lot of tweaks and experience with the kernel, drivers and OS code-base on one hand, and a lot of extensive long-term test and quality assurance on the other hand. Given that Android is a rather old and established OS I saw that it has pretty good power consumption. Phoronix does this kind of comparissions but I was not able to find much about Ubuntu Touch. Does Ubuntu Touch consume less than Android, do you have data on some platforms compared?

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  • "Growing Green"

    Organizations are managing more information, reducing fuel consumption, and developing clean energy with Oracle technology.

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  • Given a trace of packets, how would you group them into flows?

    - by zxcvbnm
    I've tried it these ways so far: 1) Make a hash with the source IP/port and destination IP/port as keys. Each position in the hash is a list of packets. The hash is then saved in a file, with each flow separated by some special characters/line. Problem: Not enough memory for large traces. 2) Make a hash with the same key as above, but only keep in memory the file handles. Each packet is then put into the hash[key] that points to the right file. Problems: Too many flows/files (~200k) and it might run out of memory as well. 3) Hash the source IP/port and destination IP/port, then put the info inside a file. The difference between 2 and 3 is that here the files are opened and closed for each operation, so I don't have to worry about running out of memory because I opened too many at the same time. Problems: WAY too slow, same number of files as 2 so also impractical. 4) Make a hash of the source IP/port pairs and then iterate over the whole trace for each flow. Take the packets that are part of that flow and place them into the output file. Problem: Suppose I have a 60 MB trace that has 200k flows. This way, I would process, say, a 60 MB file 200k times. Maybe removing the packets as I iterate would make it not so painful, but so far I'm not sure this would be a good solution. 5) Split them by IP source/destination and then create a single file for each one, separating the flows by special characters. Still too many files (+50k). Right now I'm using Ruby to do it, which might've been a bad idea, I guess. Currently I've filtered the traces with tshark so that they only have relevant info, so I can't really make them any smaller. I thought about loading everything in memory as described in 1) using C#/Java/C++, but I was wondering if there wouldn't be a better approach here, especially since I might also run out of memory later on even with a more efficient language if I have to use larger traces. In summary, the problem I'm facing is that I either have too many files or that I run out of memory. I've also tried searching for some tool to filter the info, but I don't think there is one. The ones I've found only return some statistics and wouldn't scan for every flow as I need.

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  • Few doubts regarding Bitmaps , Images & `using` blocks

    - by imageWorker
    I caught up in this problem. http://stackoverflow.com/questions/2559826/garbage-collector-not-doing-its-job-memory-consumption-1-5gb-outofmemory-exc I feel that there is something wrong in my understanding. Please clarify these things. Destructor & IDisposable.Dispose are two methods for freeing resources that are not not under the control of .NET. Which means, everything except memory. right? using blocks are just better way of calling IDisposable.Dispose() method of an object. This is the main code I'm referring to. class someclass { static someMethod(Bitmap img) { Bitmap bmp = new Bitmap(img); //statement1 // some code here and return } } here is class I'm using for testing: class someotherClass { public static voide Main() { foreach (string imagePath in imagePathsArray) { using (Bitmap img1 = new Bitmap(imagePath)) { someclass.someMethod(img1); // does some more processing on `img1` } } } } Is there any memory leak with statement1? Question1: If each image size is say 10MB. Then does this bmp object occupy atleast 10MB? What I mean is, will it make completely new copy of entire image? or just refer to it? Question2:should I or should I not put the statement1 in using block? My Argument: We should not. Because using is not for freeing memory but for freeing the resources (file handle in this case). If I use it in using block. It closes file handle here encapsulated by this bmp object. It means we are also closing filehandle for the caller's img1 object. Which is not correct? As of the memory leak. No there is no scope of memory leak here. Because reference bmp is destroyed when this method is returned. Which leaves memory it refered without any pointer. So, its garbage collected. Am I right? Edit: class someclass { static Bitmap someMethod(Bitmap img) { Bitmap bmp = new Bitmap(img); //can I use `using` block on this enclosing `return bmp`; ??? // do some processing on bmp here return bmp; } }

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  • lxc containers hangs after upgrade to 13.10

    - by doug123
    I have 3 lxc containers. They were all working fine on 12.10 and I upgraded the containers with do-release-upgrade on the containers to 13.04 and 13.10 and that worked great. Then I upgraded the host to 13.04 and then 13.10 and now the 3 containers hang with this: >lxc-start -n as1 -l DEBUG -o $(tty) lxc-start 1383145786.513 INFO lxc_start_ui - using rcfile /var/lib/lxc/as1/config lxc-start 1383145786.513 WARN lxc_log - lxc_log_init called with log already initialized lxc-start 1383145786.513 INFO lxc_apparmor - aa_enabled set to 1 lxc-start 1383145786.514 DEBUG lxc_conf - allocated pty '/dev/pts/2' (5/6) lxc-start 1383145786.514 DEBUG lxc_conf - allocated pty '/dev/pts/13' (7/8) lxc-start 1383145786.514 DEBUG lxc_conf - allocated pty '/dev/pts/14' (9/10) lxc-start 1383145786.514 DEBUG lxc_conf - allocated pty '/dev/pts/15' (11/12) lxc-start 1383145786.514 DEBUG lxc_conf - allocated pty '/dev/pts/17' (13/14) lxc-start 1383145786.514 DEBUG lxc_conf - allocated pty '/dev/pts/18' (15/16) lxc-start 1383145786.514 DEBUG lxc_conf - allocated pty '/dev/pts/19' (17/18) lxc-start 1383145786.514 DEBUG lxc_conf - allocated pty '/dev/pts/20' (19/20) lxc-start 1383145786.514 INFO lxc_conf - tty's configured lxc-start 1383145786.514 DEBUG lxc_start - sigchild handler set lxc-start 1383145786.514 DEBUG lxc_console - opening /dev/tty for console peer lxc-start 1383145786.514 DEBUG lxc_console - using '/dev/tty' as console lxc-start 1383145786.514 DEBUG lxc_console - 6242 got SIGWINCH fd 25 lxc-start 1383145786.514 DEBUG lxc_console - set winsz dstfd:22 cols:177 rows:53 lxc-start 1383145786.514 INFO lxc_start - 'as1' is initialized lxc-start 1383145786.522 DEBUG lxc_start - Not dropping cap_sys_boot or watching utmp lxc-start 1383145786.524 DEBUG lxc_conf - mac address of host interface 'vethB4L35W' changed to private fe:7c:96:a0:ae:29 lxc-start 1383145786.525 DEBUG lxc_conf - instanciated veth 'vethB4L35W/vethVC61K2', index is '26' lxc-start 1383145786.529 DEBUG lxc_cgroup - cgroup 'memory.limit_in_bytes' set to '20G' lxc-start 1383145786.529 DEBUG lxc_cgroup - cgroup 'cpuset.cpus' set to '12-23' lxc-start 1383145786.529 INFO lxc_cgroup - cgroup has been setup lxc-start 1383145786.555 DEBUG lxc_conf - move 'eth0' to '6249' lxc-start 1383145786.555 INFO lxc_conf - 'as1' hostname has been setup lxc-start 1383145786.575 DEBUG lxc_conf - 'eth0' has been setup lxc-start 1383145786.575 INFO lxc_conf - network has been setup lxc-start 1383145786.575 INFO lxc_conf - looking at .44 42 252:0 / / rw,relatime - ext4 /dev/mapper/limitorderbook1-root rw,errors=remount-ro,data=ordered . lxc-start 1383145786.575 INFO lxc_conf - now p is . /. lxc-start 1383145786.575 INFO lxc_conf - looking at .52 44 0:5 / /dev rw,relatime - devtmpfs udev rw,size=32961632k,nr_inodes=8240408,mode=755 . lxc-start 1383145786.575 INFO lxc_conf - now p is . /dev. lxc-start 1383145786.575 INFO lxc_conf - looking at .61 52 0:11 / /dev/pts rw,nosuid,noexec,relatime - devpts devpts rw,mode=600,ptmxmode=000 . lxc-start 1383145786.575 INFO lxc_conf - now p is . /dev/pts. lxc-start 1383145786.575 INFO lxc_conf - looking at .68 44 0:15 / /run rw,nosuid,noexec,relatime - tmpfs tmpfs rw,size=6594456k,mode=755 . lxc-start 1383145786.575 INFO lxc_conf - now p is . /run. lxc-start 1383145786.575 INFO lxc_conf - looking at .69 68 0:18 / /run/lock rw,nosuid,nodev,noexec,relatime - tmpfs none rw,size=5120k . lxc-start 1383145786.575 INFO lxc_conf - now p is . /run/lock. lxc-start 1383145786.575 INFO lxc_conf - looking at .72 68 0:19 / /run/shm rw,nosuid,nodev,relatime - tmpfs none rw . lxc-start 1383145786.575 INFO lxc_conf - now p is . /run/shm. lxc-start 1383145786.575 INFO lxc_conf - looking at .73 68 0:21 / /run/user rw,nosuid,nodev,noexec,relatime - tmpfs none rw,size=102400k,mode=755 . lxc-start 1383145786.575 INFO lxc_conf - now p is . /run/user. lxc-start 1383145786.575 INFO lxc_conf - looking at .76 44 0:14 / /sys rw,nosuid,nodev,noexec,relatime - sysfs sysfs rw . lxc-start 1383145786.575 INFO lxc_conf - now p is . /sys. lxc-start 1383145786.575 INFO lxc_conf - looking at .77 76 0:16 / /sys/fs/cgroup rw,relatime - tmpfs none rw,size=4k,mode=755 . lxc-start 1383145786.575 INFO lxc_conf - now p is . /sys/fs/cgroup. lxc-start 1383145786.575 INFO lxc_conf - looking at .78 77 0:20 / /sys/fs/cgroup/cpuset rw,relatime - cgroup cgroup rw,cpuset,clone_children . lxc-start 1383145786.575 INFO lxc_conf - now p is . /sys/fs/cgroup/cpuset. lxc-start 1383145786.575 INFO lxc_conf - looking at .79 77 0:23 / /sys/fs/cgroup/cpu rw,relatime - cgroup cgroup rw,cpu . lxc-start 1383145786.575 INFO lxc_conf - now p is . /sys/fs/cgroup/cpu. lxc-start 1383145786.575 INFO lxc_conf - looking at .80 77 0:24 / /sys/fs/cgroup/cpuacct rw,relatime - cgroup cgroup rw,cpuacct . lxc-start 1383145786.575 INFO lxc_conf - now p is . /sys/fs/cgroup/cpuacct. lxc-start 1383145786.575 INFO lxc_conf - looking at .81 77 0:25 / /sys/fs/cgroup/memory rw,relatime - cgroup cgroup rw,memory . lxc-start 1383145786.575 INFO lxc_conf - now p is . /sys/fs/cgroup/memory. lxc-start 1383145786.575 INFO lxc_conf - looking at .82 77 0:26 / /sys/fs/cgroup/devices rw,relatime - cgroup cgroup rw,devices . lxc-start 1383145786.575 INFO lxc_conf - now p is . /sys/fs/cgroup/devices. lxc-start 1383145786.575 INFO lxc_conf - looking at .83 77 0:27 / /sys/fs/cgroup/freezer rw,relatime - cgroup cgroup rw,freezer . lxc-start 1383145786.575 INFO lxc_conf - now p is . /sys/fs/cgroup/freezer. lxc-start 1383145786.575 INFO lxc_conf - looking at .84 77 0:28 / /sys/fs/cgroup/blkio rw,relatime - cgroup cgroup rw,blkio . lxc-start 1383145786.575 INFO lxc_conf - now p is . /sys/fs/cgroup/blkio. lxc-start 1383145786.575 INFO lxc_conf - looking at .85 77 0:29 / /sys/fs/cgroup/perf_event rw,relatime - cgroup cgroup rw,perf_event . lxc-start 1383145786.575 INFO lxc_conf - now p is . /sys/fs/cgroup/perf_event. lxc-start 1383145786.575 INFO lxc_conf - looking at .94 77 0:30 / /sys/fs/cgroup/hugetlb rw,relatime - cgroup cgroup rw,hugetlb . lxc-start 1383145786.575 INFO lxc_conf - now p is . /sys/fs/cgroup/hugetlb. lxc-start 1383145786.575 INFO lxc_conf - looking at .95 77 0:31 / /sys/fs/cgroup/systemd rw,nosuid,nodev,noexec,relatime - cgroup systemd rw,name=systemd . lxc-start 1383145786.575 INFO lxc_conf - now p is . /sys/fs/cgroup/systemd. lxc-start 1383145786.575 INFO lxc_conf - looking at .96 76 0:17 / /sys/fs/fuse/connections rw,relatime - fusectl none rw . lxc-start 1383145786.575 INFO lxc_conf - now p is . /sys/fs/fuse/connections. lxc-start 1383145786.575 INFO lxc_conf - looking at .98 76 0:6 / /sys/kernel/debug rw,relatime - debugfs none rw . lxc-start 1383145786.575 INFO lxc_conf - now p is . /sys/kernel/debug. lxc-start 1383145786.575 INFO lxc_conf - looking at .101 76 0:10 / /sys/kernel/security rw,relatime - securityfs none rw . lxc-start 1383145786.575 INFO lxc_conf - now p is . /sys/kernel/security. lxc-start 1383145786.575 INFO lxc_conf - looking at .102 76 0:22 / /sys/fs/pstore rw,relatime - pstore none rw . lxc-start 1383145786.575 INFO lxc_conf - now p is . /sys/fs/pstore. lxc-start 1383145786.575 INFO lxc_conf - looking at .103 44 0:3 / /proc rw,nosuid,nodev,noexec,relatime - proc proc rw . lxc-start 1383145786.575 INFO lxc_conf - now p is . /proc. lxc-start 1383145786.575 INFO lxc_conf - looking at .104 44 9:2 / /data rw,relatime - ext4 /dev/md2 rw,errors=remount-ro,data=ordered . lxc-start 1383145786.575 INFO lxc_conf - now p is . /data. lxc-start 1383145786.575 INFO lxc_conf - looking at .105 44 8:1 / /boot rw,relatime - ext2 /dev/sda1 rw,errors=continue . lxc-start 1383145786.575 INFO lxc_conf - now p is . /boot. lxc-start 1383145786.576 DEBUG lxc_conf - mounted '/data/srv/lxc/as1' on '/usr/lib/x86_64-linux-gnu/lxc' lxc-start 1383145786.576 DEBUG lxc_conf - mounted 'none' on '/usr/lib/x86_64-linux-gnu/lxc//dev/pts', type 'devpts' lxc-start 1383145786.576 DEBUG lxc_conf - mounted 'none' on '/usr/lib/x86_64-linux-gnu/lxc//proc', type 'proc' lxc-start 1383145786.576 DEBUG lxc_conf - mounted 'none' on '/usr/lib/x86_64-linux-gnu/lxc//sys', type 'sysfs' lxc-start 1383145786.576 DEBUG lxc_conf - mounted 'none' on '/usr/lib/x86_64-linux-gnu/lxc//run', type 'tmpfs' lxc-start 1383145786.576 INFO lxc_conf - mount points have been setup lxc-start 1383145786.577 INFO lxc_conf - console has been setup lxc-start 1383145786.577 INFO lxc_conf - 8 tty(s) has been setup lxc-start 1383145786.577 INFO lxc_conf - rootfs path is ./data/srv/lxc/as1., mount is ./usr/lib/x86_64-linux-gnu/lxc. lxc-start 1383145786.577 INFO lxc_apparmor - I am 1, /proc/self points to 1 lxc-start 1383145786.577 DEBUG lxc_conf - created '/usr/lib/x86_64-linux-gnu/lxc/lxc_putold' directory lxc-start 1383145786.577 DEBUG lxc_conf - mountpoint for old rootfs is '/usr/lib/x86_64-linux-gnu/lxc/lxc_putold' lxc-start 1383145786.577 DEBUG lxc_conf - pivot_root syscall to '/usr/lib/x86_64-linux-gnu/lxc' successful lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/dev/pts' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/run/lock' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/run/shm' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/run/user' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/sys/fs/cgroup/cpuset' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/sys/fs/cgroup/cpu' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/sys/fs/cgroup/cpuacct' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/sys/fs/cgroup/memory' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/sys/fs/cgroup/devices' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/sys/fs/cgroup/freezer' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/sys/fs/cgroup/blkio' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/sys/fs/cgroup/perf_event' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/sys/fs/cgroup/hugetlb' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/sys/fs/cgroup/systemd' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/sys/fs/fuse/connections' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/sys/kernel/debug' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/sys/kernel/security' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/sys/fs/pstore' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/proc' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/data' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/boot' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/dev' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/run' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/sys/fs/cgroup' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/sys' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold' lxc-start 1383145786.577 INFO lxc_conf - created new pts instance lxc-start 1383145786.578 DEBUG lxc_conf - drop capability 'sys_boot' (22) lxc-start 1383145786.578 DEBUG lxc_conf - capabilities have been setup lxc-start 1383145786.578 NOTICE lxc_conf - 'as1' is setup. lxc-start 1383145786.578 DEBUG lxc_cgroup - cgroup 'memory.limit_in_bytes' set to '20G' lxc-start 1383145786.578 DEBUG lxc_cgroup - cgroup 'cpuset.cpus' set to '12-23' lxc-start 1383145786.578 INFO lxc_cgroup - cgroup has been setup lxc-start 1383145786.578 INFO lxc_apparmor - setting up apparmor lxc-start 1383145786.578 INFO lxc_apparmor - changed apparmor profile to lxc-container-default lxc-start 1383145786.578 NOTICE lxc_start - exec'ing '/sbin/init' lxc-start 1383145786.578 INFO lxc_conf - looking at .15 20 0:14 / /sys rw,nosuid,nodev,noexec,relatime - sysfs sysfs rw . lxc-start 1383145786.578 INFO lxc_conf - now p is . /sys. lxc-start 1383145786.578 INFO lxc_conf - looking at .16 20 0:3 / /proc rw,nosuid,nodev,noexec,relatime - proc proc rw . lxc-start 1383145786.578 INFO lxc_conf - now p is . /proc. lxc-start 1383145786.578 INFO lxc_conf - looking at .17 20 0:5 / /dev rw,relatime - devtmpfs udev rw,size=32961632k,nr_inodes=8240408,mode=755 . lxc-start 1383145786.578 INFO lxc_conf - now p is . /dev. lxc-start 1383145786.578 INFO lxc_conf - looking at .18 17 0:11 / /dev/pts rw,nosuid,noexec,relatime - devpts devpts rw,mode=600,ptmxmode=000 . lxc-start 1383145786.578 INFO lxc_conf - now p is . /dev/pts. lxc-start 1383145786.578 INFO lxc_conf - looking at .19 20 0:15 / /run rw,nosuid,noexec,relatime - tmpfs tmpfs rw,size=6594456k,mode=755 . lxc-start 1383145786.578 INFO lxc_conf - now p is . /run. lxc-start 1383145786.578 INFO lxc_conf - looking at .20 1 252:0 / / rw,relatime - ext4 /dev/mapper/limitorderbook1-root rw,errors=remount-ro,data=ordered . lxc-start 1383145786.578 INFO lxc_conf - now p is . /. lxc-start 1383145786.578 INFO lxc_conf - looking at .22 15 0:16 / /sys/fs/cgroup rw,relatime - tmpfs none rw,size=4k,mode=755 . lxc-start 1383145786.578 INFO lxc_conf - now p is . /sys/fs/cgroup. lxc-start 1383145786.578 INFO lxc_conf - looking at .23 15 0:17 / /sys/fs/fuse/connections rw,relatime - fusectl none rw . lxc-start 1383145786.578 INFO lxc_conf - now p is . /sys/fs/fuse/connections. lxc-start 1383145786.578 INFO lxc_conf - looking at .24 15 0:6 / /sys/kernel/debug rw,relatime - debugfs none rw . lxc-start 1383145786.579 INFO lxc_conf - now p is . /sys/kernel/debug. lxc-start 1383145786.579 INFO lxc_conf - looking at .25 15 0:10 / /sys/kernel/security rw,relatime - securityfs none rw . lxc-start 1383145786.579 INFO lxc_conf - now p is . /sys/kernel/security. lxc-start 1383145786.579 INFO lxc_conf - looking at .26 19 0:18 / /run/lock rw,nosuid,nodev,noexec,relatime - tmpfs none rw,size=5120k . lxc-start 1383145786.579 INFO lxc_conf - now p is . /run/lock. lxc-start 1383145786.579 INFO lxc_conf - looking at .27 19 0:19 / /run/shm rw,nosuid,nodev,relatime - tmpfs none rw . lxc-start 1383145786.579 INFO lxc_conf - now p is . /run/shm. lxc-start 1383145786.579 INFO lxc_conf - looking at .28 22 0:20 / /sys/fs/cgroup/cpuset rw,relatime - cgroup cgroup rw,cpuset,clone_children . lxc-start 1383145786.579 INFO lxc_conf - now p is . /sys/fs/cgroup/cpuset. lxc-start 1383145786.579 INFO lxc_conf - looking at .29 19 0:21 / /run/user rw,nosuid,nodev,noexec,relatime - tmpfs none rw,size=102400k,mode=755 . lxc-start 1383145786.579 INFO lxc_conf - now p is . /run/user. lxc-start 1383145786.579 INFO lxc_conf - looking at .30 15 0:22 / /sys/fs/pstore rw,relatime - pstore none rw . lxc-start 1383145786.579 INFO lxc_conf - now p is . /sys/fs/pstore. lxc-start 1383145786.579 INFO lxc_conf - looking at .31 22 0:23 / /sys/fs/cgroup/cpu rw,relatime - cgroup cgroup rw,cpu . lxc-start 1383145786.579 INFO lxc_conf - now p is . /sys/fs/cgroup/cpu. lxc-start 1383145786.579 INFO lxc_conf - looking at .32 22 0:24 / /sys/fs/cgroup/cpuacct rw,relatime - cgroup cgroup rw,cpuacct . lxc-start 1383145786.579 INFO lxc_conf - now p is . /sys/fs/cgroup/cpuacct. lxc-start 1383145786.579 INFO lxc_conf - looking at .33 22 0:25 / /sys/fs/cgroup/memory rw,relatime - cgroup cgroup rw,memory . lxc-start 1383145786.579 INFO lxc_conf - now p is . /sys/fs/cgroup/memory. lxc-start 1383145786.579 INFO lxc_conf - looking at .34 22 0:26 / /sys/fs/cgroup/devices rw,relatime - cgroup cgroup rw,devices . lxc-start 1383145786.579 INFO lxc_conf - now p is . /sys/fs/cgroup/devices. lxc-start 1383145786.579 INFO lxc_conf - looking at .35 22 0:27 / /sys/fs/cgroup/freezer rw,relatime - cgroup cgroup rw,freezer . lxc-start 1383145786.579 INFO lxc_conf - now p is . /sys/fs/cgroup/freezer. lxc-start 1383145786.579 INFO lxc_conf - looking at .36 22 0:28 / /sys/fs/cgroup/blkio rw,relatime - cgroup cgroup rw,blkio . lxc-start 1383145786.579 INFO lxc_conf - now p is . /sys/fs/cgroup/blkio. lxc-start 1383145786.579 INFO lxc_conf - looking at .37 22 0:29 / /sys/fs/cgroup/perf_event rw,relatime - cgroup cgroup rw,perf_event . lxc-start 1383145786.579 INFO lxc_conf - now p is . /sys/fs/cgroup/perf_event. lxc-start 1383145786.579 INFO lxc_conf - looking at .38 22 0:30 / /sys/fs/cgroup/hugetlb rw,relatime - cgroup cgroup rw,hugetlb . lxc-start 1383145786.579 INFO lxc_conf - now p is . /sys/fs/cgroup/hugetlb. lxc-start 1383145786.579 INFO lxc_conf - looking at .39 20 9:2 / /data rw,relatime - ext4 /dev/md2 rw,errors=remount-ro,data=ordered . lxc-start 1383145786.579 INFO lxc_conf - now p is . /data. lxc-start 1383145786.579 INFO lxc_conf - looking at .40 20 8:1 / /boot rw,relatime - ext2 /dev/sda1 rw,errors=continue . lxc-start 1383145786.579 INFO lxc_conf - now p is . /boot. lxc-start 1383145786.579 INFO lxc_conf - looking at .41 22 0:31 / /sys/fs/cgroup/systemd rw,nosuid,nodev,noexec,relatime - cgroup systemd rw,name=systemd . lxc-start 1383145786.579 INFO lxc_conf - now p is . /sys/fs/cgroup/systemd. lxc-start 1383145786.579 NOTICE lxc_start - '/sbin/init' started with pid '6249' lxc-start 1383145786.579 WARN lxc_start - invalid pid for SIGCHLD <4>init: ureadahead main process (7) terminated with status 5 <4>init: console-font main process (94) terminated with status 1 And it will just sit there like that for hours at least. The container becomes pingable but I can't ssh and if I try lxc-console -n as1 I get a blank screen. If I do lxc-stop -n as1 or ^C in the window where it has hung I get: ^CTERM environment variable not set. <4>init: plymouth-upstart-bridge main process (192) terminated with status 1 <4>init: hwclock-save main process (187) terminated with status 70 * Asking all remaining processes to terminate... ...done. * All processes ended within 1 seconds... ...done. * Deactivating swap... ...fail! mount: cannot mount block device /dev/md2 read-only * Will now restart But after 20 minutes it hasn't restarted. Any ideas why these containers are hanging?

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  • CLSF & CLK 2013 Trip Report by Jeff Liu

    - by jamesmorris
    This is a contributed post from Jeff Liu, lead XFS developer for the Oracle mainline Linux kernel team. Recently, I attended both the China Linux Storage and Filesystem workshop (CLSF), and the China Linux Kernel conference (CLK), which were held in Shanghai. Here are the highlights for both events. CLSF - 17th October XFS update (led by Jeff Liu) XFS keeps rapid progress with a lot of changes, especially focused on the infrastructure/performance improvements as well as  new feature development.  This can be reflected with a sample statistics among XFS/Ext4+JBD2/Btrfs via: # git diff --stat --minimal -C -M v3.7..v3.12-rc4 -- fs/xfs|fs/ext4+fs/jbd2|fs/btrfs XFS: 141 files changed, 27598 insertions(+), 19113 deletions(-) Ext4+JBD2: 39 files changed, 10487 insertions(+), 5454 deletions(-) Btrfs: 70 files changed, 19875 insertions(+), 8130 deletions(-) What made up those changes in XFS? Self-describing metadata(CRC32c). This is a new feature and it contributed about 70% code changes, it can be enabled via `mkfs.xfs -m crc=1 /dev/xxx` for v5 superblock. Transaction log space reservation improvements. With this change, we can calculate the log space reservation at mount time rather than runtime to reduce the the CPU overhead. User namespace support. So both XFS and USERNS can be enabled on kernel configuration begin from Linux 3.10. Thanks Dwight Engen's efforts for this thing. Split project/group quota inodes. Originally, project quota can not be enabled with group quota at the same time because they were share the same quota file inode, now it works but only for v5 super block. i.e, CRC enabled. CONFIG_XFS_WARN, an new lightweight runtime debugger which can be deployed in production environment. Readahead log object recovery, this change can speed up the log replay progress significantly. Speculative preallocation inode tracking, clearing and throttling. The main purpose is to deal with inodes with post-EOF space due to speculative preallocation, support improved quota management to free up a significant amount of unwritten space when at or near EDQUOT. It support backgroup scanning which occurs on a longish interval(5 mins by default, tunable), and on-demand scanning/trimming via ioctl(2). Bitter arguments ensued from this session, especially for the comparison between Ext4 and Btrfs in different areas, I have to spent a whole morning of the 1st day answering those questions. We basically agreed on XFS is the best choice in Linux nowadays because: Stable, XFS has a good record in stability in the past 10 years. Fengguang Wu who lead the 0-day kernel test project also said that he has observed less error than other filesystems in the past 1+ years, I own it to the XFS upstream code reviewer, they always performing serious code review as well as testing. Good performance for large/small files, XFS does not works very well for small files has already been an old story for years. Best choice (maybe) for distributed PB filesystems. e.g, Ceph recommends delopy OSD daemon on XFS because Ext4 has limited xattr size. Best choice for large storage (>16TB). Ext4 does not support a single file more than around 15.95TB. Scalability, any objection to XFS is best in this point? :) XFS is better to deal with transaction concurrency than Ext4, why? The maximum size of the log in XFS is 2038MB compare to 128MB in Ext4. Misc. Ext4 is widely used and it has been proved fast/stable in various loads and scenarios, XFS just need more customers, and Btrfs is still on the road to be a manhood. Ceph Introduction (Led by Li Wang) This a hot topic.  Li gave us a nice introduction about the design as well as their current works. Actually, Ceph client has been included in Linux kernel since 2.6.34 and supported by Openstack since Folsom but it seems that it has not yet been widely deployment in production environment. Their major work is focus on the inline data support to separate the metadata and data storage, reduce the file access time, i.e, a file access need communication twice, fetch the metadata from MDS and then get data from OSD, and also, the small file access is limited by the network latency. The solution is, for the small files they would like to store the data at metadata so that when accessing a small file, the metadata server can push both metadata and data to the client at the same time. In this way, they can reduce the overhead of calculating the data offset and save the communication to OSD. For this feature, they have only run some small scale testing but really saw noticeable improvements. Test environment: Intel 2 CPU 12 Core, 64GB RAM, Ubuntu 12.04, Ceph 0.56.6 with 200GB SATA disk, 15 OSD, 1 MDS, 1 MON. The sequence read performance for 1K size files improved about 50%. I have asked Li and Zheng Yan (the core developer of Ceph, who also worked on Btrfs) whether Ceph is really stable and can be deployed at production environment for large scale PB level storage, but they can not give a positive answer, looks Ceph even does not spread over Dreamhost (subject to confirmation). From Li, they only deployed Ceph for a small scale storage(32 nodes) although they'd like to try 6000 nodes in the future. Improve Linux swap for Flash storage (led by Shaohua Li) Because of high density, low power and low price, flash storage (SSD) is a good candidate to partially replace DRAM. A quick answer for this is using SSD as swap. But Linux swap is designed for slow hard disk storage, so there are a lot of challenges to efficiently use SSD for swap. SWAPOUT swap_map scan swap_map is the in-memory data structure to track swap disk usage, but it is a slow linear scan. It will become a bottleneck while finding many adjacent pages in the use of SSD. Shaohua Li have changed it to a cluster(128K) list, resulting in O(1) algorithm. However, this apporoach needs restrictive cluster alignment and only enabled for SSD. IO pattern In most cases, the swap io is in interleaved pattern because of mutiple reclaimers or a free cluster is shared by all reclaimers. Even though block layer can merge interleaved IO to some extent, but we cannot count on it completely. Hence the per-cpu cluster is added base on the previous change, it can help reclaimer do sequential IO and the block layer will be easier to merge IO. TLB flush: If we're reclaiming one active page, we should first move the page from active lru list to inactive lru list, and then reclaim the page from inactive lru to swap it out. During the process, we need to clear PTE twice: first is 'A'(ACCESS) bit, second is 'P'(PRESENT) bit. Processors need to send lots of ipi which make the TLB flush really expensive. Some works have been done to improve this, including rework smp_call_functiom_many() or remove the first TLB flush in x86, but there still have some arguments here and only parts of works have been pushed to mainline. SWAPIN: Page fault does iodepth=1 sync io, but it's a little waste if only issue a page size's IO. The obvious solution is doing swap readahead. But the current in-kernel swap readahead is arbitary(always 8 pages), and it always doesn't perform well for both random and sequential access workload. Shaohua introduced a new flag for madvise(MADV_WILLNEED) to do swap prefetch, so the changes happen in userspace API and leave the in-kernel readahead unchanged(but I think some improvement can also be done here). SWAP discard As we know, discard is important for SSD write throughout, but the current swap discard implementation is synchronous. He changed it to async discard which allow discard and write run in the same time. Meanwhile, the unit of discard is also optimized to cluster. Misc: lock contention For many concurrent swapout and swapin , the lock contention such as anon_vma or swap_lock is high, so he changed the swap_lock to a per-swap lock. But there still have some lock contention in very high speed SSD because of swapcache address_space lock. Zproject (led by Bob Liu) Bob gave us a very nice introduction about the current memory compression status. Now there are 3 projects(zswap/zram/zcache) which all aim at smooth swap IO storm and promote performance, but they all have their own pros and cons. ZSWAP It is implemented based on frontswap API and it uses a dynamic allocater named Zbud to allocate free pages. Zbud means pairs of zpages are "buddied" and it can only store at most two compressed pages in one page frame, so the max compress ratio is 50%. Each page frame is lru-linked and can do shink in memory pressure. If the compressed memory pool reach its limitation, shink or reclaim happens. It decompress the page frame into two new allocated pages and then write them to real swap device, but it can fail when allocating the two pages. ZRAM Acts as a compressed ramdisk and used as swap device, and it use zsmalloc as its allocator which has high density but may have fragmentation issues. Besides, page reclaim is hard since it will need more pages to uncompress and free just one page. ZRAM is preferred by embedded system which may not have any real swap device. Now both ZRAM and ZSWAP are in driver/staging tree, and in the mm community there are some disscussions of merging ZRAM into ZSWAP or viceversa, but no agreement yet. ZCACHE Handles file page compression but it is removed out of staging recently. From industry (led by Tang Jie, LSI) An LSI engineer introduced several new produces to us. The first is raid5/6 cards that it use full stripe writes to improve performance. The 2nd one he introduced is SandForce flash controller, who can understand data file types (data entropy) to reduce write amplification (WA) for nearly all writes. It's called DuraWrite and typical WA is 0.5. What's more, if enable its Dynamic Logical Capacity function module, the controller can do data compression which is transparent to upper layer. LSI testing shows that with this virtual capacity enables 1x TB drive can support up to 2x TB capacity, but the application must monitor free flash space to maintain optimal performance and to guard against free flash space exhaustion. He said the most useful application is for datebase. Another thing I think it's worth to mention is that a NV-DRAM memory in NMR/Raptor which is directly exposed to host system. Applications can directly access the NV-DRAM via a memory address - using standard system call mmap(). He said that it is very useful for database logging now. This kind of NVM produces are beginning to appear in recent years, and it is said that Samsung is building a research center in China for related produces. IMHO, NVM will bring an effect to current os layer especially on file system, e.g. its journaling may need to redesign to fully utilize these nonvolatile memory. OCFS2 (led by Canquan Shen) Without a doubt, HuaWei is the biggest contributor to OCFS2 in the past two years. They have posted 46 upstream patches and 39 patches have been merged. Their current project is based on 32/64 nodes cluster, but they also tried 128 nodes at the experimental stage. The major work they are working is to support ATS (atomic test and set), it can be works with DLM at the same time. Looks this idea is inspired by the vmware VMFS locking, i.e, http://blogs.vmware.com/vsphere/2012/05/vmfs-locking-uncovered.html CLK - 18th October 2013 Improving Linux Development with Better Tools (Andi Kleen) This talk focused on how to find/solve bugs along with the Linux complexity growing. Generally, we can do this with the following kind of tools: Static code checkers tools. e.g, sparse, smatch, coccinelle, clang checker, checkpatch, gcc -W/LTO, stanse. This can help check a lot of things, simple mistakes, complex problems, but the challenges are: some are very slow, false positives, may need a concentrated effort to get false positives down. Especially, no static checker I found can follow indirect calls (“OO in C”, common in kernel): struct foo_ops { int (*do_foo)(struct foo *obj); } foo->do_foo(foo); Dynamic runtime checkers, e.g, thread checkers, kmemcheck, lockdep. Ideally all kernel code would come with a test suite, then someone could run all the dynamic checkers. Fuzzers/test suites. e.g, Trinity is a great tool, it finds many bugs, but needs manual model for each syscall. Modern fuzzers around using automatic feedback, but notfor kernel yet: http://taviso.decsystem.org/making_software_dumber.pdf Debuggers/Tracers to understand code, e.g, ftrace, can dump on events/oops/custom triggers, but still too much overhead in many cases to run always during debug. Tools to read/understand source, e.g, grep/cscope work great for many cases, but do not understand indirect pointers (OO in C model used in kernel), give us all “do_foo” instances: struct foo_ops { int (*do_foo)(struct foo *obj); } = { .do_foo = my_foo }; foo>do_foo(foo); That would be great to have a cscope like tool that understands this based on types/initializers XFS: The High Performance Enterprise File System (Jeff Liu) [slides] I gave a talk for introducing the disk layout, unique features, as well as the recent changes.   The slides include some charts to reflect the performances between XFS/Btrfs/Ext4 for small files. About a dozen users raised their hands when I asking who has experienced with XFS. I remembered that when I asked the same question in LinuxCon/Japan, only 3 people raised their hands, but they are Chris Mason, Ric Wheeler, and another attendee. The attendee questions were mainly focused on stability, and comparison with other file systems. Linux Containers (Feng Gao) The speaker introduced us that the purpose for those kind of namespaces, include mount/UTS/IPC/Network/Pid/User, as well as the system API/ABI. For the userspace tools, He mainly focus on the Libvirt LXC rather than us(LXC). Libvirt LXC is another userspace container management tool, implemented as one type of libvirt driver, it can manage containers, create namespace, create private filesystem layout for container, Create devices for container and setup resources controller via cgroup. In this talk, Feng also mentioned another two possible new namespaces in the future, the 1st is the audit, but not sure if it should be assigned to user namespace or not. Another is about syslog, but the question is do we really need it? In-memory Compression (Bob Liu) Same as CLSF, a nice introduction that I have already mentioned above. Misc There were some other talks related to ACPI based memory hotplug, smart wake-affinity in scheduler etc., but my head is not big enough to record all those things. -- Jeff Liu

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