Search Results

Search found 9 results on 1 pages for 'cybershadow'.

Page 1/1 | 1 

• One True Event Loop

  - by CyberShadow

  Simple programs that collect data from only one system need only one event loop. For example, Windows applications have the message loop, POSIX network programs usually have a select/epoll/etc. loop at their core, pure SDL games use SDL's event loop. But what if you need to collect events from several subsystems? Such as an SDL game which doesn't use SDL_net for networking. I can think of several solutions: Polling (ugh) Put each event loop in its own thread, and: Send messages to the main thread, which collects and processes the events, or Place the event-processing code of each thread in a critical section, so that the threads can wait for events asynchronously but process them synchronously Choose one subsystem for the main event loop, and pass events from other subsystems via that subsystem as custom messages (for example, the Windows message loop and custom messages, or a socket select() loop and passing events via a loopback connection). Option 2.1 is more interesting on platforms where message-passing is a well-developed threading primitive (e.g. in the D programming language), but 2.2 looks like the best option to me.

  Read the article

• Disk usage treemap software for headless Linux

  - by CyberShadow

  There are some programs which can display used disk space using a treemap, such as WinDirStat for Windows and KDirStat for KDE/Linux: I'm looking for something similar, but for a headless Linux box. Alternatively, what are other good ways to visualize used disk space with just SSH access?

  Read the article

• Can the Intel C600-series SAS controller RAID SATA drives?

  - by CyberShadow

  (Sorry if this is off-topic - technically this is a home workstation setting, but is regarding mostly-server technology.) I have a GA-X79S-UP5-WIFI motherboard and four ST3000DM001 drives, and the IRST manager isn't letting me put the drives in a RAID (it lists them, but the option to select the C600-series controller is simply grayed out). Have I done a mistake? Do I need SAS drives to RAID them on the SAS controller?

  Read the article

• How to stop Apache from crashing my entire server?

  - by CyberShadow

  I maintain a Gentoo server with a few services, including Apache. It's fairly low-end (2GB of RAM and a low-end CPU with 2 cores). My problem is that, despite my best efforts, an over-loaded Apache crashes the entire server. In fact, at this point I'm close to being convinced that Linux is a horrible operating system that isn't worth anyone's time looking for stability under load. Things I tried: Adjusting oom_adj for the root Apache process (and thus all its children). That had close to no effect. When Apache was overloaded it would bring the system to a grind, as the system paged out everything else before it got to kill anything. Turning off swap. Didn't help, it would unload memory paged to binaries of processes and other files on /, thus causing the same effect. Putting it in a memory-limited cgroup (limited to 512 MB of RAM, 1/4th of the total). This "worked", at least in my own stress tests - except the server keeps crashing under load (basically stalling all other processes, inaccessible via SSH, etc.) Running it with idle I/O priority. This wasn't a very good idea in the end, because it just caused the system load to climb indefinitely (into the thousands) with almost no visible effect - until you tried to access an unbuffered part of the disk. This caused the task to freeze. (So much for good I/O scheduling, eh?) Limiting the number of concurrent connections to Apache. Setting the number too low caused web sites to become unresponsive due to most slots being occupied with long requests (file downloads). I tried various Apache MPMs without much success (prefork, event, itk). Switching from prefork/event+php-cgi+suphp to itk+mod_php. This improved performance, but didn't solve the actual problem. Switching I/O schedulers (cfq to deadline). Just to stress this out: I don't care if Apache itself goes down under load, I just want the rest of my system to remain stable. Of course, having Apache recover quickly after a brief period of intensive load would be great to have, but one step at a time. Right now I am mostly dumbfounded by how can humanity, in this day and age, design an operating system where such a seemingly simple task (don't allow one system component to crash the entire system) seems practically impossible - or at least, very hard to do. Please don't suggest things like VMs or "BUY MORE RAM". Some more information gathered with a friend's help: The processes hang when the cgroup oom killer is invoked. Here's the call trace: [<ffffffff8104b94b>] ? prepare_to_wait+0x70/0x7b [<ffffffff810a9c73>] mem_cgroup_handle_oom+0xdf/0x180 [<ffffffff810a9559>] ? memcg_oom_wake_function+0x0/0x6d [<ffffffff810aa041>] __mem_cgroup_try_charge+0x32d/0x478 [<ffffffff810aac67>] mem_cgroup_charge_common+0x48/0x73 [<ffffffff81081c98>] ? __lru_cache_add+0x60/0x62 [<ffffffff810aadc3>] mem_cgroup_newpage_charge+0x3b/0x4a [<ffffffff8108ec38>] handle_mm_fault+0x305/0x8cf [<ffffffff813c6276>] ? schedule+0x6ae/0x6fb [<ffffffff8101f568>] do_page_fault+0x214/0x22b [<ffffffff813c7e1f>] page_fault+0x1f/0x30 At this point, the apache memory cgroup is practically deadlocked, and burning CPU in syscalls (all with the above call trace). This seems like a problem in the cgroup implementation...

  Read the article

• Disk usage treemap software for headless Linux

  - by CyberShadow

  There are some programs which can display used disk space using a treemap, such as WinDirStat for Windows and KDirStat for KDE/Linux: I'm looking for something similar, but for a headless Linux box. (E.g. run console data collection program on the server, then load the file in a graphical program in a GUI environment.) Alternatively, what are other good ways to get a structured used disk space representation, with just SSH access?

  Read the article

• "Exclusive" DirectDraw palette isn't actually exclusive

  - by CyberShadow

  We're maintaining an old video game that uses a full-screen 256-color graphics mode with DirectDraw. The problem is, some applications running in the background sometimes try to change the system palette while the game is running, which results in corrupted graphics. We can (sometimes) detect when this happens by processing the WM_PALETTECHANGED message. A few update versions ago we added logging (just log the window title/class/process name), which helped users identify offending applications and close them. MSN Live Messenger was a common culprit. The problem got worse when we found out that Windows Vista (and 7) does it "by itself". The WM_PALETTECHANGED parameters point towards CSRSS and the desktop window. In Vista, a workaround that often worked was to open any folder (Computer, Documents, etc.) and leave it open while running the game. Sounds ridiculous, but it worked - in most cases. In Windows 7, not even this workaround worked any more. Users found that stopping some services (Windows Update and the indexing service) also resolved the problem on some configurations. Some time ago I just started trying random things in hope of finding a solution. I found that setting the GDI palette (using Create/SelectPalette) before setting the DirectDraw palette (using IDirectDrawPalette::SetEntries) would restore the palette after it became corrupted (WM_PALETTECHANGED handler). SetSystemPaletteUse and calling SetPalette on the primary surface helped some more. However, there is still perceivable flickering when an application tries to steal the palette, which is especially prominent during fades. Question: is there a way to get a "real" exclusive palette, which completely disallows other applications changing the Windows palette as long as our game retains focus?

  Read the article

• Exact textual representation of an IEEE "double"

  - by CyberShadow

  I need to represent an IEEE 754-1985 double (64-bit) floating point number in a human-readable textual form, with the condition that the textual form can be parsed back into exactly the same (bit-wise) number. Is this possible/practical to do without just printing the raw bytes? If yes, code to do this would be much appreciated.

  Read the article

• How to get all <img> tags inside a text selection?

  - by CyberShadow

  I've looked around for a while, but there doesn't seem to be a simple way to do this. jQuery doesn't help the in least, it seems to entirely lack any support for selection or DOM ranges. Something which I hoped would be as simple as $.selection.filter('img') seems to only be doable with dozens of lines of code dealing with manually enumerating elements in ranges and browser implementation inconsistencies (though ierange helps here). Any other shortcuts?

  Read the article

• How to link Delphi with C++?

  - by CyberShadow

  cpp.cpp extern "C" char* GetText() { return "Hello, world!"; } delphi.dpr {$APPTYPE CONSOLE} {$LINK 'cpp.obj'} function _GetText: PChar; cdecl; external; begin WriteLn(_GetText); end. I can't get this to work, no matter what I try. I tried various calling conventions, playing with underscores. even creating a .c wrapper for the .cpp code (but then the .c wrapper doesn't "see" any .cpp symbols). I'm about to give up and use DLLs. Any suggestions?

  Read the article

1