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• Why using Fragments?

  - by ahmed_khan_89

  I have read the documentation and some other questions' threads about this topic and I don't really feel convinced; I don't see clearly the limits of use of this technique. Fragments are now seen as a Best Practice; every Activity should be basically a support for one or more Fragments and not call a layout directly. Fragments are created in order to: allow the Activity to use many fragments, to change between them, to reuse these units... == the Fragment is totally dependent to the Context of an activity , so if I need something generic that I can reuse and handle in many Activities, I can create my own custom layouts or Views ... I will not care about this additional Complexity Developing Layer that fragments would add. a better handling to different resolution == OK for tablets/phones in case of long process that we can show two (or more) fragments in the same Activity in Tablets, and one by one in phones. But why would I use fragments always ? handling callbacks to navigate between Fragments (i.e: if the user is Logged-in I show a fragment else I show another fragment). === Just try to see how many bugs facebook SDK Log-in have because of this, to understand that it is really (?) ... considering that an Android Application is based on Activities... Adding another life cycles in the Activity would be better to design an Application... I mean the modules, the scenarios, the data management and the connectivity would be better designed, in that way. === This is an answer of someone who's used to see the Android SDK and Android Framework with a Fragments vision. I don't think it's wrong, but I am not sure it will give good results... And it is really abstract... ==== Why would I complicate my life, coding more, in using them always? else, why is it a best practice if it's just a tool for some cases? what are these cases?

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• Which is more expensive multiple conditional branches or multiple relational expression in a single condition?

  - by bman

  Which is more expensive in terms of processing costs if ( x < 20 && z == "M") { // statements 3 } if ( x >= 20 && w && x <= 65) { // statements 1 } if( x >= 20 &&z != "M"){ // statements 2 } or this if ( x < 20 ) { if( z == 'M') // statements 3; } else if ( x <= 65 && w == true ) // statements 1; if ( z == 'F' ) // statements 2; }

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• Does low latency code sometimes have to be "ugly"?

  - by user997112

  (This is mainly aimed at those who have specific knowledge of low latency systems, to avoid people just answering with unsubstantiated opinions). Do you feel there is a trade-off between writing "nice" object orientated code and writing very fast low latency code? For instance, avoiding virtual functions in C++/the overhead of polymorphism etc- re-writing code which looks nasty, but is very fast etc? It stands to reason- who cares if it looks ugly (so long as its maintainable)- if you need speed, you need speed? I would be interested to hear from people who have worked in such areas.

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• unexplainable packet drops with 5 ethernet NICs and low traffic on Ubuntu

  - by jon

  I'm stuck on problem where my machine started to drops packets with no sign of ANY system load or high interrupt usage after an upgrade to Ubuntu 12.04. My server is a network monitoring sensor, running Ubuntu LTS 12.04, it passively collects packets from 5 interfaces doing network intrusion type stuff. Before the upgrade I managed to collect 200+GB of packets a day while writing them to disk with around 0% packet loss depending on the day with the help of CPU affinity and NIC IRQ to CPU bindings. Now I lose a great deal of packets with none of my applications running and at very low PPS rate which a modern workstation NIC would have no trouble with. Specs: x64 Xeon 4 cores 3.2 Ghz 16 GB RAM NICs: 5 Intel Pro NICs using the e1000 driver (NAPI). [1] eth0 and eth1 are integrated NICs (in the motherboard) There are 2 other PCI-X network cards, each with 2 Ethernet ports. 3 of the interfaces are running at Gigabit Ethernet, the others are not because they're attached to hubs. Specs: [2] http://support.dell.com/support/edocs/systems/pe2850/en/ug/t1390aa.htm uptime 17:36:00 up 1:43, 2 users, load average: 0.00, 0.01, 0.05 # uname -a Linux nms 3.2.0-29-generic #46-Ubuntu SMP Fri Jul 27 17:03:23 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux I also have the CPU governor set to performance mode and irqbalance off. The problem still occurs with them on. # lspci -t -vv -[0000:00]-+-00.0 Intel Corporation E7520 Memory Controller Hub +-02.0-[01-03]--+-00.0-[02]----0e.0 Dell PowerEdge Expandable RAID controller 4 | \-00.2-[03]-- +-04.0-[04]-- +-05.0-[05-07]--+-00.0-[06]----07.0 Intel Corporation 82541GI Gigabit Ethernet Controller | \-00.2-[07]----08.0 Intel Corporation 82541GI Gigabit Ethernet Controller +-06.0-[08-0a]--+-00.0-[09]--+-04.0 Intel Corporation 82546EB Gigabit Ethernet Controller (Copper) | | \-04.1 Intel Corporation 82546EB Gigabit Ethernet Controller (Copper) | \-00.2-[0a]--+-02.0 Digium, Inc. Wildcard TE210P/TE212P dual-span T1/E1/J1 card 3.3V | +-03.0 Intel Corporation 82546EB Gigabit Ethernet Controller (Copper) | \-03.1 Intel Corporation 82546EB Gigabit Ethernet Controller (Copper) +-1d.0 Intel Corporation 82801EB/ER (ICH5/ICH5R) USB UHCI Controller #1 +-1d.1 Intel Corporation 82801EB/ER (ICH5/ICH5R) USB UHCI Controller #2 +-1d.2 Intel Corporation 82801EB/ER (ICH5/ICH5R) USB UHCI Controller #3 +-1d.7 Intel Corporation 82801EB/ER (ICH5/ICH5R) USB2 EHCI Controller +-1e.0-[0b]----0d.0 Advanced Micro Devices [AMD] nee ATI RV100 QY [Radeon 7000/VE] +-1f.0 Intel Corporation 82801EB/ER (ICH5/ICH5R) LPC Interface Bridge \-1f.1 Intel Corporation 82801EB/ER (ICH5/ICH5R) IDE Controller I believe the NIC nor the NIC drivers are dropping the packets because ethtool reports 0 under rx_missed_errors and rx_no_buffer_count for each interface. On the old system, if it couldn't keep up this is where the drops would be. I drop packets on multiple interfaces just about every second, usually in small increments of 2-4. I tried all these sysctl values, I'm currently using the uncommented ones. # cat /etc/sysctl.conf # high net.core.netdev_max_backlog = 3000000 net.core.rmem_max = 16000000 net.core.rmem_default = 8000000 # defaults #net.core.netdev_max_backlog = 1000 #net.core.rmem_max = 131071 #net.core.rmem_default = 163480 # moderate #net.core.netdev_max_backlog = 10000 #net.core.rmem_max = 33554432 #net.core.rmem_default = 33554432 Here's an example of an interface stats report with ethtool. They are all the same, nothing is out of the ordinary ( I think ), so I'm only going to show one: ethtool -S eth2 NIC statistics: rx_packets: 7498 tx_packets: 0 rx_bytes: 2722585 tx_bytes: 0 rx_broadcast: 327 tx_broadcast: 0 rx_multicast: 1504 tx_multicast: 0 rx_errors: 0 tx_errors: 0 tx_dropped: 0 multicast: 1504 collisions: 0 rx_length_errors: 0 rx_over_errors: 0 rx_crc_errors: 0 rx_frame_errors: 0 rx_no_buffer_count: 0 rx_missed_errors: 0 tx_aborted_errors: 0 tx_carrier_errors: 0 tx_fifo_errors: 0 tx_heartbeat_errors: 0 tx_window_errors: 0 tx_abort_late_coll: 0 tx_deferred_ok: 0 tx_single_coll_ok: 0 tx_multi_coll_ok: 0 tx_timeout_count: 0 tx_restart_queue: 0 rx_long_length_errors: 0 rx_short_length_errors: 0 rx_align_errors: 0 tx_tcp_seg_good: 0 tx_tcp_seg_failed: 0 rx_flow_control_xon: 0 rx_flow_control_xoff: 0 tx_flow_control_xon: 0 tx_flow_control_xoff: 0 rx_long_byte_count: 2722585 rx_csum_offload_good: 0 rx_csum_offload_errors: 0 alloc_rx_buff_failed: 0 tx_smbus: 0 rx_smbus: 0 dropped_smbus: 01 # ifconfig eth0 Link encap:Ethernet HWaddr 00:11:43:e0:e2:8c UP BROADCAST RUNNING NOARP PROMISC ALLMULTI MULTICAST MTU:1500 Metric:1 RX packets:373348 errors:16 dropped:95 overruns:0 frame:16 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:356830572 (356.8 MB) TX bytes:0 (0.0 B) eth1 Link encap:Ethernet HWaddr 00:11:43:e0:e2:8d UP BROADCAST RUNNING NOARP PROMISC ALLMULTI MULTICAST MTU:1500 Metric:1 RX packets:13616 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:8690528 (8.6 MB) TX bytes:0 (0.0 B) eth2 Link encap:Ethernet HWaddr 00:04:23:e1:77:6a UP BROADCAST RUNNING NOARP PROMISC ALLMULTI MULTICAST MTU:1500 Metric:1 RX packets:7750 errors:0 dropped:471 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:2780935 (2.7 MB) TX bytes:0 (0.0 B) eth3 Link encap:Ethernet HWaddr 00:04:23:e1:77:6b UP BROADCAST RUNNING NOARP PROMISC ALLMULTI MULTICAST MTU:1500 Metric:1 RX packets:5112 errors:0 dropped:206 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:639472 (639.4 KB) TX bytes:0 (0.0 B) eth4 Link encap:Ethernet HWaddr 00:04:23:b6:35:6c UP BROADCAST RUNNING NOARP PROMISC ALLMULTI MULTICAST MTU:1500 Metric:1 RX packets:961467 errors:0 dropped:935 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:958561305 (958.5 MB) TX bytes:0 (0.0 B) eth5 Link encap:Ethernet HWaddr 00:04:23:b6:35:6d inet addr:192.168.1.6 Bcast:192.168.1.255 Mask:255.255.255.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:4264 errors:0 dropped:16 overruns:0 frame:0 TX packets:699 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:572228 (572.2 KB) TX bytes:124456 (124.4 KB) I tried the defaults, then started to play around with settings. I wasn't using any flow control and I increased the RxDescriptor count to 4096 before the upgrade as well without any problems. # cat /etc/modprobe.d/e1000.conf options e1000 XsumRX=0,0,0,0,0 RxDescriptors=4096,4096,4096,4096,4096 FlowControl=0,0,0,0,0 debug=16 Here's my network configuration file, I turned off checksumming and various offloading mechanisms along with setting CPU affinity with heavy use interfaces getting an entire CPU and light use interfaces sharing a CPU. I used these settings prior to the upgrade without problems. # cat /etc/network/interfaces # The loopback network interface auto lo iface lo inet loopback # The primary network interface auto eth0 iface eth0 inet manual pre-up /sbin/ethtool -G eth0 rx 4096 tx 0 pre-up /sbin/ethtool -K eth0 gro off gso off rx off pre-up /sbin/ethtool -A eth0 rx off autoneg off up ifconfig eth0 0.0.0.0 -arp promisc mtu 1500 allmulti txqueuelen 0 up post-up echo "4" > /proc/irq/48/smp_affinity down ifconfig eth0 down post-down /sbin/ethtool -G eth0 rx 256 tx 256 post-down /sbin/ethtool -K eth0 gro on gso on rx on post-down /sbin/ethtool -A eth0 rx on autoneg on auto eth1 iface eth1 inet manual pre-up /sbin/ethtool -G eth1 rx 4096 tx 0 pre-up /sbin/ethtool -K eth1 gro off gso off rx off pre-up /sbin/ethtool -A eth1 rx off autoneg off up ifconfig eth1 0.0.0.0 -arp promisc mtu 1500 allmulti txqueuelen 0 up post-up echo "4" > /proc/irq/49/smp_affinity down ifconfig eth1 down post-down /sbin/ethtool -G eth1 rx 256 tx 256 post-down /sbin/ethtool -K eth1 gro on gso on rx on post-down /sbin/ethtool -A eth1 rx on autoneg on auto eth2 iface eth2 inet manual pre-up /sbin/ethtool -G eth2 rx 4096 tx 0 pre-up /sbin/ethtool -K eth2 gro off gso off rx off pre-up /sbin/ethtool -A eth2 rx off autoneg off up ifconfig eth2 0.0.0.0 -arp promisc mtu 1500 allmulti txqueuelen 0 up post-up echo "1" > /proc/irq/82/smp_affinity down ifconfig eth2 down post-down /sbin/ethtool -G eth2 rx 256 tx 256 post-down /sbin/ethtool -K eth2 gro on gso on rx on post-down /sbin/ethtool -A eth2 rx on autoneg on auto eth3 iface eth3 inet manual pre-up /sbin/ethtool -G eth3 rx 4096 tx 0 pre-up /sbin/ethtool -K eth3 gro off gso off rx off pre-up /sbin/ethtool -A eth3 rx off autoneg off up ifconfig eth3 0.0.0.0 -arp promisc mtu 1500 allmulti txqueuelen 0 up post-up echo "2" > /proc/irq/83/smp_affinity down ifconfig eth3 down post-down /sbin/ethtool -G eth3 rx 256 tx 256 post-down /sbin/ethtool -K eth3 gro on gso on rx on post-down /sbin/ethtool -A eth3 rx on autoneg on auto eth4 iface eth4 inet manual pre-up /sbin/ethtool -G eth4 rx 4096 tx 0 pre-up /sbin/ethtool -K eth4 gro off gso off rx off pre-up /sbin/ethtool -A eth4 rx off autoneg off up ifconfig eth4 0.0.0.0 -arp promisc mtu 1500 allmulti txqueuelen 0 up post-up echo "4" > /proc/irq/77/smp_affinity down ifconfig eth4 down post-down /sbin/ethtool -G eth4 rx 256 tx 256 post-down /sbin/ethtool -K eth4 gro on gso on rx on post-down /sbin/ethtool -A eth4 rx on autoneg on auto eth5 iface eth5 inet static pre-up /etc/fw.conf address 192.168.1.1 netmask 255.255.255.0 broadcast 192.168.1.255 gateway 192.168.1.1 dns-nameservers 192.168.1.2 192.168.1.3 up ifconfig eth5 up post-up echo "8" > /proc/irq/77/smp_affinity down ifconfig eth5 down Here's a few examples of packet drops, i ran one after another, probabling totaling 3 or 4 seconds. You can see increases in the drops from the 1st and 3rd. This was a non-busy time, very little traffic. # awk '{ print $1,$5 }' /proc/net/dev Inter-| face drop eth3: 225 lo: 0 eth2: 505 eth1: 0 eth5: 17 eth0: 105 eth4: 1034 # awk '{ print $1,$5 }' /proc/net/dev Inter-| face drop eth3: 225 lo: 0 eth2: 507 eth1: 0 eth5: 17 eth0: 105 eth4: 1034 # awk '{ print $1,$5 }' /proc/net/dev Inter-| face drop eth3: 227 lo: 0 eth2: 512 eth1: 0 eth5: 17 eth0: 105 eth4: 1039 I tried the pci=noacpi options. With and without, it's the same. This is what my interrupt stats looked like before the upgrade, after, with ACPI on PCI it showed multiple NICs bound to an interrupt and shared with other devices such as USB drives which I didn't like so I think i'm going to keep it with ACPI off as it's easier to designate sole purpose interrupts. Is there any advantage I would have using the default i.e. ACPI w/ PCI. ? # cat /etc/default/grub | grep CMD_LINE GRUB_CMDLINE_LINUX_DEFAULT="ipv6.disable=1 noacpi pci=noacpi" GRUB_CMDLINE_LINUX="" # cat /proc/interrupts CPU0 CPU1 CPU2 CPU3 0: 45 0 0 16 IO-APIC-edge timer 1: 1 0 0 7936 IO-APIC-edge i8042 2: 0 0 0 0 XT-PIC-XT-PIC cascade 6: 0 0 0 3 IO-APIC-edge floppy 8: 0 0 0 1 IO-APIC-edge rtc0 9: 0 0 0 0 IO-APIC-edge acpi 12: 0 0 0 1809 IO-APIC-edge i8042 14: 1 0 0 4498 IO-APIC-edge ata_piix 15: 0 0 0 0 IO-APIC-edge ata_piix 16: 0 0 0 0 IO-APIC-fasteoi uhci_hcd:usb2 18: 0 0 0 1350 IO-APIC-fasteoi uhci_hcd:usb4, radeon 19: 0 0 0 0 IO-APIC-fasteoi uhci_hcd:usb3 23: 0 0 0 4099 IO-APIC-fasteoi ehci_hcd:usb1 38: 0 0 0 61963 IO-APIC-fasteoi megaraid 48: 0 0 1002319 4 IO-APIC-fasteoi eth0 49: 0 0 38772 3 IO-APIC-fasteoi eth1 77: 0 0 130076 432159 IO-APIC-fasteoi eth4 78: 0 0 0 23917 IO-APIC-fasteoi eth5 82: 1329033 0 0 4 IO-APIC-fasteoi eth2 83: 0 4886525 0 6 IO-APIC-fasteoi eth3 NMI: 5 6 4 5 Non-maskable interrupts LOC: 61409 57076 64257 114764 Local timer interrupts SPU: 0 0 0 0 Spurious interrupts IWI: 0 0 0 0 IRQ work interrupts RES: 17956 25333 13436 14789 Rescheduling interrupts CAL: 22436 607 539 478 Function call interrupts TLB: 1525 1458 4600 4151 TLB shootdowns TRM: 0 0 0 0 Thermal event interrupts THR: 0 0 0 0 Threshold APIC interrupts MCE: 0 0 0 0 Machine check exceptions MCP: 16 16 16 16 Machine check polls ERR: 0 MIS: 0 Here's sample output of vmstat, showing the system. Barebones system right now. root@nms:~# vmstat -S m 1 procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 0 0 0 14992 192 1029 0 0 56 2 419 29 1 0 99 0 0 0 0 14992 192 1029 0 0 0 0 922 27 0 0 100 0 0 0 0 14991 192 1029 0 0 0 36 763 50 0 0 100 0 0 0 0 14991 192 1029 0 0 0 0 646 35 0 0 100 0 0 0 0 14991 192 1029 0 0 0 0 722 54 0 0 100 0 0 0 0 14991 192 1029 0 0 0 0 793 27 0 0 100 0 ^C Here's dmesg output. I can't figure out why my PCI-X slots are negotiated as PCI. The network cards are all PCI-X with the exception of the integrated NICs that came with the server. In the output below it looks as if eth3 and eth2 negotiated at PCI-X speeds rather than PCI:66Mhz. Wouldn't they all drop to PCI:66Mhz? If your integrated NICs are PCI, as labeled below (eth0,eth1), then wouldn't all devices on your bus speed drop down to that slower bus speed? If not, I still don't know why only one of my NICs ( each has two ethernet ports) is labeled as PCI-X in the output below. Does that mean it is running at PCI-X speeds are is it showing that it's capable? # dmesg | grep e1000 [ 3678.349337] e1000: Intel(R) PRO/1000 Network Driver - version 7.3.21-k8-NAPI [ 3678.349342] e1000: Copyright (c) 1999-2006 Intel Corporation. [ 3678.349394] e1000 0000:06:07.0: PCI->APIC IRQ transform: INT A -> IRQ 48 [ 3678.409725] e1000 0000:06:07.0: Receive Descriptors set to 4096 [ 3678.409730] e1000 0000:06:07.0: Checksum Offload Disabled [ 3678.409734] e1000 0000:06:07.0: Flow Control Disabled [ 3678.586409] e1000 0000:06:07.0: eth0: (PCI:66MHz:32-bit) 00:11:43:e0:e2:8c [ 3678.586419] e1000 0000:06:07.0: eth0: Intel(R) PRO/1000 Network Connection [ 3678.586642] e1000 0000:07:08.0: PCI->APIC IRQ transform: INT A -> IRQ 49 [ 3678.649854] e1000 0000:07:08.0: Receive Descriptors set to 4096 [ 3678.649859] e1000 0000:07:08.0: Checksum Offload Disabled [ 3678.649863] e1000 0000:07:08.0: Flow Control Disabled [ 3678.826436] e1000 0000:07:08.0: eth1: (PCI:66MHz:32-bit) 00:11:43:e0:e2:8d [ 3678.826444] e1000 0000:07:08.0: eth1: Intel(R) PRO/1000 Network Connection [ 3678.826627] e1000 0000:09:04.0: PCI->APIC IRQ transform: INT A -> IRQ 82 [ 3679.093266] e1000 0000:09:04.0: Receive Descriptors set to 4096 [ 3679.093271] e1000 0000:09:04.0: Checksum Offload Disabled [ 3679.093275] e1000 0000:09:04.0: Flow Control Disabled [ 3679.130239] e1000 0000:09:04.0: eth2: (PCI-X:133MHz:64-bit) 00:04:23:e1:77:6a [ 3679.130246] e1000 0000:09:04.0: eth2: Intel(R) PRO/1000 Network Connection [ 3679.130449] e1000 0000:09:04.1: PCI->APIC IRQ transform: INT B -> IRQ 83 [ 3679.397312] e1000 0000:09:04.1: Receive Descriptors set to 4096 [ 3679.397318] e1000 0000:09:04.1: Checksum Offload Disabled [ 3679.397321] e1000 0000:09:04.1: Flow Control Disabled [ 3679.434350] e1000 0000:09:04.1: eth3: (PCI-X:133MHz:64-bit) 00:04:23:e1:77:6b [ 3679.434360] e1000 0000:09:04.1: eth3: Intel(R) PRO/1000 Network Connection [ 3679.434553] e1000 0000:0a:03.0: PCI->APIC IRQ transform: INT A -> IRQ 77 [ 3679.704072] e1000 0000:0a:03.0: Receive Descriptors set to 4096 [ 3679.704077] e1000 0000:0a:03.0: Checksum Offload Disabled [ 3679.704081] e1000 0000:0a:03.0: Flow Control Disabled [ 3679.738364] e1000 0000:0a:03.0: eth4: (PCI:33MHz:64-bit) 00:04:23:b6:35:6c [ 3679.738371] e1000 0000:0a:03.0: eth4: Intel(R) PRO/1000 Network Connection [ 3679.738538] e1000 0000:0a:03.1: PCI->APIC IRQ transform: INT B -> IRQ 78 [ 3680.046060] e1000 0000:0a:03.1: eth5: (PCI:33MHz:64-bit) 00:04:23:b6:35:6d [ 3680.046067] e1000 0000:0a:03.1: eth5: Intel(R) PRO/1000 Network Connection [ 3682.132415] e1000: eth0 NIC Link is Up 100 Mbps Half Duplex, Flow Control: None [ 3682.224423] e1000: eth1 NIC Link is Up 100 Mbps Half Duplex, Flow Control: None [ 3682.316385] e1000: eth2 NIC Link is Up 100 Mbps Half Duplex, Flow Control: None [ 3682.408391] e1000: eth3 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: None [ 3682.500396] e1000: eth4 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: None [ 3682.708401] e1000: eth5 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX At first I thought it was the NIC drivers but I'm not so sure. I really have no idea where else to look at the moment. Any help is greatly appreciated as I'm struggling with this. If you need more information just ask. Thanks! [1]http://www.cs.fsu.edu/~baker/devices/lxr/http/source/linux/Documentation/networking/e1000.txt?v=2.6.11.8 [2] http://support.dell.com/support/edocs/systems/pe2850/en/ug/t1390aa.htm

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• Huge performance difference between two web servers, odd behavior seen using process monitor

  - by Francis Gagnon

  We have two Coldfusion servers that have a huge performance difference running the exact same code on the exact same input data. The code in questions instantiates a large amount of CFCs (Coldfusion Components, which are similar to objects in OOP languages). I compared the two servers by running Process Monitor and then calling the problematic code on both machines. I learned two things. First, Coldfusion opens CFC files every time it instantiates an object. Both servers do this, so it cannot be the cause of the performance difference. Second, the fast server opens the CFC files directly while the server with the performance problem seems to navigate its way through the path until it reaches the desired CFC file. It does this for every file, even the ones it has previously loaded, and because the code instantiates so many CFCs it becomes very slow. See below the partial Promon traces that show this behavior. It can take over 60 seconds for the slow server to do what the fast one does in 2 seconds. Can anyone tell me what causes this behavior? Is it a Coldfusion setting? Since Coldfusion runs on top of Java, is it a Java setting? Is it an OS option? The fast server is running Windows XP and I think the slow server is a Windows Server 2003. Bonus question: Coldfusion doesn't seem to perform any READ FILE operations on any of the CFC or CFM files. How can this be? Sample of the fast server opening CFC files: 11:25:14.5588975 jrun.exe QueryOpen C:\CF\wwwroot\APP\com\HtmlUtils.cfc 11:25:14.5592758 jrun.exe CreateFile C:\CF\wwwroot\APP\com\HtmlUtils.cfc 11:25:14.5595024 jrun.exe QueryBasicInformationFile C:\CF\wwwroot\APP\com\HtmlUtils.cfc 11:25:14.5595940 jrun.exe CloseFile C:\CF\wwwroot\APP\com\HtmlUtils.cfc 11:25:14.5599628 jrun.exe CreateFile C:\CF\wwwroot\APP\com\HtmlUtils.cfc 11:25:14.5601600 jrun.exe QueryBasicInformationFile C:\CF\wwwroot\APP\com\HtmlUtils.cfc 11:25:14.5602463 jrun.exe CloseFile C:\CF\wwwroot\APP\com\HtmlUtils.cfc Equivalent sample of the slow server opening CFC files: 11:15:08.1249230 jrun.exe CreateFile D:\ 11:15:08.1250100 jrun.exe QueryDirectory D:\org 11:15:08.1252852 jrun.exe CloseFile D:\ 11:15:08.1259670 jrun.exe CreateFile D:\org 11:15:08.1260319 jrun.exe QueryDirectory D:\org\cli 11:15:08.1260769 jrun.exe CloseFile D:\org 11:15:08.1269451 jrun.exe CreateFile D:\org\cli 11:15:08.1270613 jrun.exe QueryDirectory D:\org\cli\cpn 11:15:08.1271140 jrun.exe CloseFile D:\org\cli 11:15:08.1279312 jrun.exe CreateFile D:\org\cli\cpn 11:15:08.1280086 jrun.exe QueryDirectory D:\org\cli\cpn\APP 11:15:08.1280789 jrun.exe CloseFile D:\org\cli\cpn 11:15:08.1291034 jrun.exe CreateFile D:\org\cli\cpn\APP 11:15:08.1291709 jrun.exe QueryDirectory D:\org\cli\cpn\APP\com 11:15:08.1292224 jrun.exe CloseFile D:\org\cli\cpn\APP 11:15:08.1300568 jrun.exe CreateFile D:\org\cli\cpn\APP\com 11:15:08.1301321 jrun.exe QueryDirectory D:\org\cli\cpn\APP\com\HtmlUtils.cfc 11:15:08.1301843 jrun.exe CloseFile D:\org\cli\cpn\APP\com 11:15:08.1312049 jrun.exe CreateFile D:\org\cli\cpn\APP\com\HtmlUtils.cfc 11:15:08.1314409 jrun.exe QueryBasicInformationFile D:\org\cli\cpn\APP\com\HtmlUtils.cfc 11:15:08.1314633 jrun.exe CloseFile D:\org\cli\cpn\APP\com\HtmlUtils.cfc 11:15:08.1315881 jrun.exe CreateFile D:\ 11:15:08.1316379 jrun.exe QueryDirectory D:\org 11:15:08.1316926 jrun.exe CloseFile D:\ 11:15:08.1330951 jrun.exe CreateFile D:\org 11:15:08.1338656 jrun.exe QueryDirectory D:\org\cli 11:15:08.1339118 jrun.exe CloseFile D:\org 11:15:08.1526468 jrun.exe CreateFile D:\org\cli 11:15:08.1527295 jrun.exe QueryDirectory D:\org\cli\cpn 11:15:08.1527989 jrun.exe CloseFile D:\org\cli 11:15:08.1531977 jrun.exe CreateFile D:\org\cli\cpn 11:15:08.1532589 jrun.exe QueryDirectory D:\org\cli\cpn\APP 11:15:08.1533575 jrun.exe CloseFile D:\org\cli\cpn 11:15:08.1538457 jrun.exe CreateFile D:\org\cli\cpn\APP 11:15:08.1539083 jrun.exe QueryDirectory D:\org\cli\cpn\APP\com 11:15:08.1539553 jrun.exe CloseFile D:\org\cli\cpn\APP 11:15:08.1544126 jrun.exe CreateFile D:\org\cli\cpn\APP\com 11:15:08.1544980 jrun.exe QueryDirectory D:\org\cli\cpn\APP\com\HtmlUtils.cfc 11:15:08.1545482 jrun.exe CloseFile D:\org\cli\cpn\APP\com 11:15:08.1551034 jrun.exe CreateFile D:\org\cli\cpn\APP\com\HtmlUtils.cfc 11:15:08.1552878 jrun.exe QueryBasicInformationFile D:\org\cli\cpn\APP\com\HtmlUtils.cfc 11:15:08.1553044 jrun.exe CloseFile D:\org\cli\cpn\APP\com\HtmlUtils.cfc Thanks

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• Expected IOPS for log writing on PS6000X SAN?

  - by dssz

  Customer is experiencing poor Sybase ASE 15 performance on a PS6000X SAN with 16 X 450GB 10K in RAID-50. The server is a Dell R710 running 2003 server R2 64bit in ESX 4.0.0,256968 I've used sqlio to benchmark the sequential write performance of 4KB blocks on the drive. sqlio -kW -t1 -s600 -dE -o1 -fsequential -b4 -BH -LS sqliotestfile.dat Result is 1900 IOPS. However, when Sybase is running a sustained workload of small inserts SAN HQ shows a consistent 590 IOPS (and 100% 4K write activity). It also shows that the write latency increases to 1.2ms from <1ms. Monitoring and tests in Sybase demonstrate the performance problem is IO related and in particular there is a lot of wait time writing to the log. The SAN indicates that write caching is enabled. What IOPS should the SAN be capable of for 4k sequential write activity? Also, with write caching enabled, shouldn't the controller be batching up the 4K writes into something more efficient? Also, any tips on Sybase on ESX would be appreciated.

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• ESX 4.0 space: DASD, NAS, or ?

  - by thormj

  I put together an ESX box for better management, but its performance is a WTF item; I'm a noob at dealing with ESX, so I'm looking for a laundry-list of reading material to help me straighten this out so I can go back to .NET programming. Current storage system: We're running Raid5+Hotspare (8x500 GB spindles) on a PERC6i on a Dell 2910. Due to ESX limitatios, the PERC is showing the storage as 1x2TB + 1x800GB "partitions." I'm not sure of the setup's configuration (stride / stripe / ???) at all. Our Applications We have a SBS server as well as a minor (2x50 GB, but growing at 10GB/month) database server... Our application that lives on the database VM is CPU and I/O insense; it's a database churning excercise mixed in with a lot of computation on the data (fixing that performance is what I'm supposed to be working on)... Perfomance Issue When I do a backup, restore, or worse (copy a backup from 1 vm to another to move it to the QA VM), the entire system slows to a crawl (even "unrelated" VMs). I originally thought a DASD situation would be quite good since you had PCI-x bandwidth, but the systemwide slowdown is killing productivity. Questions What should I do to make an intelligent decision about NAS vs RAID vs SAN vs DASD? Are there sweet spots/ugly spots in the storage setup? Can you use a SSD PCI-X card in ESX for the tempdb? Good/Bad idea? Is there any way to "share" some image in a copy-on-write fashion? Most of the "Backup-Copy-Restore" is to "put a clean image on the dev boxes"; if I could have them "share" the master image, the "big copy" (2x50 GB) would only need to be done once per week instead of once per dev per week...[runtime performance isn't a concern with the dev boxes, but the backup/copy/restore kills production, SBS, and everything else on the box]

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• Building a PC, advice on SSD/Hybrid Hard Drives

  - by Jamie Hartnoll

  I am looking at building a new PC, it's mainly for office (graphics heavy) use and programming. Looking for good performance with opening and closing programs and files as well as a fast boot. I plan to have 3 primary hard drives Windows 7 Programs (photoshop etc) Current Files (There'll also be a large storage capacity back up drive, but this will be the Seagate drive I already have.) So, my question is, looking at standard "old fashioned" hard drives and SSD drives, obviously there's a massive price difference. I have been looking at drives like this: http://www.ebuyer.com/268693-corsair-120gb-force-3-ssd-cssd-f120gb3-bk-cssd-f120gb3-bk and this: http://www.ebuyer.com/321969-momentus-xt-750gb-sata-2-5in-7200rpm-hybrid-8gb-ssd-in-st750lx003 Having no experience of using either I don't know what's the most efficient thing to go for. Clearly the SSD will have better performance, but: If, for example, I had an SSD for Windows (say about 100gB), that would clearly give me the boot speed I want, then I guess my real questions are: If I were to buy one more SSD, would it give the greatest improvement on standard performance if used to store programs, or currently used files? Given that the OS is on an SSD, should I not bother with the 3 drives and instead, partition that Hybrid drive to store programs and currently used files on it? Obviously, option two is cheaper and option one could cause me storage issues, but that's when I can dump files I am not currently using onto another drive. Any, I am open to suggestions... so what do you suggest?!

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• Would an array of SSD drives be able to succesfully substitute the system memory?

  - by Florin Mircea

  I watched a few videos trying to answer this. This video (youtube.com/watch?v=eULFf6F5Ri8) shows a bunch of guys stacking 24 SSD's reaching a peak of around 2GBps r/w. That's under the limit of the worst DDR3 in this list (memorybenchmark.net/write_ddr3_amd.html) - that shows DDR3 memory performance varying from 2.78 to 6.55 Gb per second, but that video is over 3 years old. This video (youtube.com/watch?v=27GmBzQWwP0) shows a more optimistic situation, but for PCI-E SSD drives: 5 drives peaking at around 4Gb. And this other video shows that stacking up more than 3 SSD's doesn't realistically offer a substantial added performance. This and the fact that in all benchmarks the drives act quite poorly when dealing with small files (5k file read/write averaging from 10MB to around 30-40MBps) as opposed to how native memory handles such files, seems to indicate a definite NO to this question. Also, the write life cycle is indeed limited and the drives might wear out quickly, as kindly pointed out by paddy. However, I wanted to get more opinions on this. Would it be possible to at least obtain current memory performance with SSD's in RAID 0? And if so, in what circumstances? I am assuming using this configuration with a Windows OS that has a memory pagefile resident to that stack of SSD's, thus making it very fast to work with.

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• WAMP running extremely slow on WIndows 7

  - by JavaCake

  After 2 days of tough fight trying to figure out what the problem is with my Windows 7 32-bit machine at work i have nearly given up. The issue is that the pages are loaded extremely slow, the performance is both when accessed locally (127.0.0.1) or from another computer in the intranet. First to explain the system: WAMP version: Apache 2.2.22 – Mysql 5.5.24 – PHP 5.4.3 XDebug 2.1.2 XDC 1.5 PhpMyadmin 3.4.10.1 SQLBuddy 1.3.3 webGrind 1.0 DocumentRoot: Located on network drive MySQL: InnoDB Pages: PHP, MySQL, AJAX etc. So basically the changes i have made in order to get a greater performance: Changed C:\windows\system32\drivers\etc\hosts: 127.0.0.1 localhost 127.0.0.1 127.0.0.1 Modified my.ini: innodb_flush_log_at_trx_commit = 2 Modified httpd.ini: EnableMMAP on EnableSendfile on Modified php.ini: realpath_cache_size= 4m How i measure the performance is the overall loadtime of the page. I run it locally on my Mac OS X machine aswell (MAMP), and typically the frontpage loadtime is 0.06seconds but on the Windows 7 machine it is 6-10seconds. I have verified the loadtime with developertools in Chrome aswell. Furthermore the result is identical in XAMPP.

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• What are some techniques to monitor multiple instances of a piece of software?

  - by Geo Ego

  I have a piece of self-serve kiosk software that will be running at multiple sites. I'd like to monitor their status remotely. The kiosk application itself is pretty much finished. I am now in the process of creating a piece of software that will monitor all of the kiosks from a central location so that the customer can view particular details remotely (for instance, how many bills are in the acceptor's cash cartridge, what customer is currently logged in, etc.). Because I am in such an early stage of development, my options are quite open. I understand that I'm not giving very many qualifications, but I'd like to try to get a good variety of potential solutions. Some details: Kiosk software is a VB6 app running on Windows Embedded Monitoring software will be run on a modern desktop version of Windows (either XP, Vista, or 7) Database is SQL Server 2008 My initial idea was to develop a .NET app that would simply report the last database transaction for each kiosk at a set interval (say every second or so) but I'd really like for the kiosk software to report its status directly. I'm not exactly sure where to begin in terms of what modifications may need to be made to the kiosk software, and what the monitoring software will require. Links to articles on these topics would be most welcome.

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• User Experience Monitoring with Enterprise Manager Cloud Control 12c and Real User Experience Insight 12R1 Demo Now Available!

  - by JuergenKress

  For access to the Oracle demo systems please visit OPN and talk to your partner expert We are pleased to announce the availability of the Oracle real user experience Insight demo that showcases some of the key capabilities of user experience monitoring. This demo specifically focuses on business reporting, integrated performance diagnostics, tracking of customer journey’s through RUEI’s userflow tracking capabilities and it’s key performance Iidicators tracking and configuration. Demo Highlights The demo showcases the following capabilities of real user experience Insight. Application-centric dashboard Integration with Oracle Enterprise Manager 12c – JVMD, ADP and BTM Session diagnostics and user session replay Monitoring through “Key Performance Indicators” (KPI) --- create alerts/incidents FUSION Application centric dashboards & integrated BI Demo Instructions Go to the DSS website for Oracle Partners. On the Standard Demo Launchpad page, click on the link “Real User Experience Insight 12c (Aug ‘12)” (tagged as “NEW”), under the “Applications Management” section. The demo launchpad page contains a link to a detailed demo script with instructions on how to show the demo. BPM 11.1.1.5 for Apps: BPM for EBS Demo available For access to the Oracle demo systems please visit OPN and talk to your Partner Expert SOA & BPM Partner Community For regular information on Oracle SOA Suite become a member in the SOA & BPM Partner Community for registration please visit  www.oracle.com/goto/emea/soa (OPN account required) If you need support with your account please contact the Oracle Partner Business Center. Blog Twitter LinkedIn Mix Forum Technorati Tags: User Experience Monitoring,EM12c,Demo,dss SOA,IDM,SOA Community,Oracle SOA,Oracle BPM,BPM,Community,OPN,Jürgen Kress

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• SSL Slow in IE 8.0.7600.16385IC

  - by discovery.jerrya

  I'm having a performance problem on my company's web site using a specific version of IE 8 to load a page using https. Here's what I know. Server: Virtual machine running on VMWare ESX Windows Server 2003 Enterprise Edition SP 2 Tomcat 6.0.16 Client: Windows XP and Window 7 Internet Explorer 8.0.7600.16385IC Page loads/refreshes in under 1 second using HTTP. Page loads/refreshes in 15-16 seconds in HTTPS using this version of IE. Problem reproduced on multiple client machines with same IE version. Problem reproduced on multiple client machines with different Windows versions (XP and 7). No performance problem using Chrome, Firefox, Opera, or Safari from same machine. No performance problem using other versions of IE 8 on other machines. Slow load causes virtually no CPU, memory, or I/O spike on server or client machine. No performance problem on other sites using HTTPS on same client machine. The pages in question use JavaScript and innerHTML to replace the contents of div elements to create a collapsible menu, and an iframe to display some content. A couple of the div elements contain images. If I remove the iframe and the JavaScript, the performance issues go away. However, rewriting the entire site to make these changes would be very time consuming. We're in the process of replacing the whole site, but it may be 2-3 months before we do so and we really cannot live with this slowdown that long. I've already looked at several IE tuning options, such as disabling add ons, running IE-rereg, and resetting IE, with no luck. Does anyone have any suggestions?

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• nVidia performance with newer X and newer driver abysmal with Compiz

  - by Nakedible

  I recently upgraded Debian to Xorg 2.9.4 and installed nvidia-glx from experimental, version 260.19.21. This was somewhat of an uphill battle as the dependencies for the experimental nvidia-glx package are still somewhat broken. I got it to work without forcing the installation of any packages and without modifying the packages. However, after the upgrade compiz performance has been abysmal. I am using the desktop wall plugin and switching viewports is really slow - takes a few seconds for each switch. In addition to this, every effect that compiz does, such as zoom animations for icons when launching applications, takes seconds. The viewport switching speed changes relative to the amount of windows on that virtual screen - empty screens switch almost at normal speed, single browser windows work almost decently, but just 4 rxvt terminals slows the switches down to a crawl. My compiz configuration should be pretty basic. Xorg is likewise configured without anything special - the only "custom" configuration is forcing the driver name to be "nvidia". I've fiddled around with the nvidia-settings and compizconfig trying different VSync settings, but none of those helped. My graphics card is: NVIDIA GPU NVS 3100M (GT218) at PCI:1:0:0 (GPU-0). This is laptop GPU that is from the Geforce GTX 200 series. Graphics card performance should naturally be no problem.

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• Will disabling hyperthreading improve performance on our SQL Server install

  - by Sam Saffron

  Related to: Current wisdom on SQL Server and Hyperthreading Recently we upgraded our Windows 2008 R2 database server from an X5470 to a X5560. The theory is both CPUs have very similar performance, if anything the X5560 is slightly faster. However, SQL Server 2008 R2 performance has been pretty bad over the last day or so and CPU usage has been pretty high. Page life expectancy is massive, we are getting almost 100% cache hit for the pages, so memory is not a problem. When I ran: SELECT * FROM sys.dm_os_wait_stats order by signal_wait_time_ms desc I got: wait_type waiting_tasks_count wait_time_ms max_wait_time_ms signal_wait_time_ms ------------------------------------------------------------ -------------------- -------------------- -------------------- -------------------- XE_TIMER_EVENT 115166 2799125790 30165 2799125065 REQUEST_FOR_DEADLOCK_SEARCH 559393 2799053973 5180 2799053973 SOS_SCHEDULER_YIELD 152289883 189948844 960 189756877 CXPACKET 234638389 2383701040 141334 118796827 SLEEP_TASK 170743505 1525669557 1406 76485386 LATCH_EX 97301008 810738519 1107 55093884 LOGMGR_QUEUE 16525384 2798527632 20751319 4083713 WRITELOG 16850119 18328365 1193 2367880 PAGELATCH_EX 13254618 8524515 11263 1670113 ASYNC_NETWORK_IO 23954146 6981220 7110 1475699 (10 row(s) affected) I also ran -- Isolate top waits for server instance since last restart or statistics clear WITH Waits AS ( SELECT wait_type, wait_time_ms / 1000. AS [wait_time_s], 100. * wait_time_ms / SUM(wait_time_ms) OVER() AS [pct], ROW_NUMBER() OVER(ORDER BY wait_time_ms DESC) AS [rn] FROM sys.dm_os_wait_stats WHERE wait_type NOT IN ('CLR_SEMAPHORE','LAZYWRITER_SLEEP','RESOURCE_QUEUE', 'SLEEP_TASK','SLEEP_SYSTEMTASK','SQLTRACE_BUFFER_FLUSH','WAITFOR','LOGMGR_QUEUE', 'CHECKPOINT_QUEUE','REQUEST_FOR_DEADLOCK_SEARCH','XE_TIMER_EVENT','BROKER_TO_FLUSH', 'BROKER_TASK_STOP','CLR_MANUAL_EVENT','CLR_AUTO_EVENT','DISPATCHER_QUEUE_SEMAPHORE', 'FT_IFTS_SCHEDULER_IDLE_WAIT','XE_DISPATCHER_WAIT', 'XE_DISPATCHER_JOIN')) SELECT W1.wait_type, CAST(W1.wait_time_s AS DECIMAL(12, 2)) AS wait_time_s, CAST(W1.pct AS DECIMAL(12, 2)) AS pct, CAST(SUM(W2.pct) AS DECIMAL(12, 2)) AS running_pct FROM Waits AS W1 INNER JOIN Waits AS W2 ON W2.rn <= W1.rn GROUP BY W1.rn, W1.wait_type, W1.wait_time_s, W1.pct HAVING SUM(W2.pct) - W1.pct < 95; -- percentage threshold And got wait_type wait_time_s pct running_pct CXPACKET 554821.66 65.82 65.82 LATCH_EX 184123.16 21.84 87.66 SOS_SCHEDULER_YIELD 37541.17 4.45 92.11 PAGEIOLATCH_SH 19018.53 2.26 94.37 FT_IFTSHC_MUTEX 14306.05 1.70 96.07 That shows huge amounts of time synchronizing queries involving parallelism (high CXPACKET). Additionally, anecdotally many of these problem queries are being executed on multiple cores (we have no MAXDOP hints anywhere in our code) The server has not been under load for more than a day or so. We are experiencing a large amount of variance with query executions, typically many queries appear to be slower that they were on our previous DB server and CPU is really high. Will disabling Hyperthreading help at reducing our CPU usage and increase throughput?

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• SQL 2005 indexed queries slower than unindexed queries

  - by uos??

  Adding a seemingly perfectly index is having an unexpectedly adverse affect on a query performance... -- [Data] has a predictable structure and a simple clustered index of the primary key: ALTER TABLE [dbo].[Data] ADD PRIMARY KEY CLUSTERED ( [ID] ) -- My query, joins on itself looking for a certain kind of "overlapping" records SELECT DISTINCT [Data].ID AS [ID] FROM dbo.[Data] AS [Data] JOIN dbo.[Data] AS [Compared] ON [Data].[A] = [Compared].[A] AND [Data].[B] = [Compared].[B] AND [Data].[C] = [Compared].[C] AND ([Data].[D] = [Compared].[D] OR [Data].[E] = [Compared].[E]) AND [Data].[F] <> [Compared].[F] WHERE 1=1 AND [Data].[A] = @A AND @CS <= [Data].[C] AND [Data].[C] < @CE -- Between a range [Data] has about a quarter-million records so far, 10% to 50% of the data satisfies the where clause depending on @A, @CS, and @CE. As is, the query takes 1 second to return about 300 rows when querying 10%, and 30 seconds to return 3000 rows when querying 50% of the data. Curiously, the estimated/actual execution plan indicates two parallel Clustered Index Scans, but the clustered index is only of the ID, which isn't part of the conditions of the query, only the output. ?? If I add this hand-crafted [IDX_A_B_C_D_E_F] index which I fully expected to improve performance, the query slows down by a factor of 8 (8 seconds for 10% & 4 minutes for 50%). The estimated/actual execution plans show an Index Seek, which seems like the right thing to be doing, but why so slow?? CREATE UNIQUE INDEX [IDX_A_B_C_D_E_F] ON [dbo].[Data] ([A], [B], [C], [D], [E], [F]) INCLUDE ([ID], [X], [Y], [Z]); The Data Engine Tuning wizard suggests a similar index with no noticeable difference in performance from this one. Moving AND [Data].[F] <> [Compared].[F] from the join condition to the where clause makes no difference in performance. I need these and other indexes for other queries. I'm sure I could hint that the query should refer to the Clustered Index, since that's currently winning - but we all know it is not as optimized as it could be, and without a proper index, I can expect the performance will get much worse with additional data. What gives?

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• How is List<T> implemented in C#?

  - by carter-boater

  I was thinking about the performance of calling List<T>.Indexof(item). I am not sure if it will be a O(n) performance for a sequential algorithm or O(log(n)) performance for a binary tree?? Thanks!

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• Performance Test and TCP tuning

  - by Mithir

  We are in the process of performance testing an application which receives tcp requests converts them to soap requests (WCF-httpBinding) which other services work on. The server is Windows Server 2008 R2. The TCP requests are received by TcpListener instance (.NET C#). There are 3 http-binded WCF services running on the same server. We have built a performance test client which goal is to simulate multiple concurrent requests(each request has to be different and recognizable by the application). We built a test running 150 requests that run on the same time (by 150 different threads), and we noticed straight away that some requests get the TCP connection slowly, but once they get it, they act fast. A single request writes twice on the same connection- request and an application ack. Although a single request+ack can take about 150ms, the 150 test takes about 7 seconds. The Problem When we try to run this test from 2 different computers we lose requests. some clients requests are getting no connection was made because the target machine actively refused it So I got here and got convinced it was because of the backlog. I changed the TcpListener parameters and did the registry AFD backlog changes written here but it still didn't work, so I inserted all of the TCP tuning suggested plus some netsh commands which were recommended, but still no change, we still get that error. Is there anything else I need to know? Are there any other solutions?

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• ASA Slow IPSec Performance with Inconsistent Window Size

  - by Brent

  I have a IPSec link between two sites over ASA 5520s running 8.4(3) and I am getting extremely poor performance when traffic passes over the IPSec VPN. CPU on the devices is ~13%, Memory at 408 MB, and active VPN sessions 2. The load on both of the the devices is particularly low. Latency between the two sites is ~40ms. Screenshot of wireshark file transfer between the two hosts over the firewall IPSec VPN performing at 10MBPS. Note the changing window size. http://imgur.com/wGTB8Cr Screenshot of wireshark file transfer between the two hosts over the firewall not going over IPSec performing at 55MBPS. Constant window size. http://imgur.com/EU23W1e I'm showing an inconsistent window size when transferring over the IPSec VPN ranging in 46,796 to 65535. When performing at 55+MBPS, the window size is consistently 65,535. Does this show a problem in my configuration of the IPSec VPN in the ASA or a Layer1/2 issue? Using ping xxxxxx -f -l I finally get a non-fragment at 1418 bytes so 1418+28 for IP/ICMP headers = 1446. I know that I have 1500 set on the ASA and Ethernet. I do have "Force Maximum segment size for TCP proxy connection to be" "1380" bytes set under Configuration Advanced TCP Options on the ASA. Using IPERF, I am getting a "TCP Window Full" every few seconds and ~3 MBPS performance. http://imgur.com/elRlMpY Show Run on the ASA http://pastebin.com/uKM4Jh76 Show cry accelerator stats http://pastebin.com/xQahnqK3

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• Fastest PNG decoder for .NET

  - by sboisse

  Our web server needs to process many compositions of large images together before sending the results to web clients. This process is performance critical because the server can receive several thousands of requests per hour. Right now our solution loads PNG files (around 1MB each) from the HD and sends them to the video card so the composition is done on the GPU. We first tried loading our images using the PNG decoder exposed by the XNA API. We saw the performance was not too good. To understand if the problem was loading from the HD or the decoding of the PNG, we modified that by loading the file in a memory stream, and then sending that memory stream to the .NET PNG decoder. The difference of performance using XNA or using System.Windows.Media.Imaging.PngBitmapDecoder class is not significant. We roughly get the same levels of performance. Our benchmarks show the following performance results: Load images from disk: 37.76ms 1% Decode PNGs: 2816.97ms 77% Load images on Video Hardware: 196.67ms 5% Composition: 87.80ms 2% Get composition result from Video Hardware: 166.21ms 5% Encode to PNG: 318.13ms 9% Store to disk: 3.96ms 0% Clean up: 53.00ms 1% Total: 3680.50ms 100% From these results we see that the slowest parts are when decoding the PNG. So we are wondering if there wouldn't be a PNG decoder we could use that would allow us to reduce the PNG decoding time. We also considered keeping the images uncompressed on the hard disk, but then each image would be 10MB in size instead of 1MB and since there are several tens of thousands of these images stored on the hard disk, it is not possible to store them all without compression.

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• Help on Website response time KPI parameters

  - by geeth

  I am working on improving website performance. Here are the list of key performance indicators I am looking at for each page Total Bytes downloaded Number of requests DNS look up time FirstByte Download time DOM content load time Total load time Is there any optimum value for each KPI to indicate website performance? Please help me in this regard.

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• FreeBSD ZFS RAID-Z2 performance issues

  - by Axel Gneiting

  I'm trying to build my own network attached storage based on FreeBSD+ZFS+standard components, but there are strange performance issues. The hardware specs are: AMD Athlon II X2 240e processor ASUS M4A78LT-M LE mainboard 2GiB Kingston ECC DDR3 (two sticks) Intel Pro/1000 CT PCIe network adapter 5x Western Digital Caviar Green 1.5TB I created a RAID-Z2 zpool from all disks. I installed FreeBSD 8.1 on that zpool following the tutorial. The SATA controllers are running in AHCI mode. Output of zpool status: pool: zroot state: ONLINE scrub: none requested config: NAME STATE READ WRITE CKSUM zroot ONLINE 0 0 0 raidz2 ONLINE 0 0 0 gptid/7ef815fc-eab6-11df-8ea4-001b2163266d ONLINE 0 0 0 gptid/80344432-eab6-11df-8ea4-001b2163266d ONLINE 0 0 0 gptid/81741ad9-eab6-11df-8ea4-001b2163266d ONLINE 0 0 0 gptid/824af5cb-eab6-11df-8ea4-001b2163266d ONLINE 0 0 0 gptid/82f98a65-eab6-11df-8ea4-001b2163266d ONLINE 0 0 0 The problem is that write performance on the pool is very very bad (<10 MB/s) and every application that is accessing the disk is unresponsive every few seconds when writing. It seems like writing is fine until the ZFS ark cache is full and then ZFS stalls the entire system I/O till it's finished writing that data. Also I'm getting kmem_malloc to small kernel panics. I've already tried to put vm.kmem_size="1500M" vm.kmem_size_max="1500M" into /boot/loader.conf, but it doesn't help. Does anyone know what's going on here? Am I really not having enough memory for ZFS to handle this RAID-Z2?

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• ORM solutions (JPA; Hibernate) vs. JDBC

  - by Grasper

  I need to be able to insert/update objects at a consistent rate of at least 8000 objects every 5 seconds in an in-memory HSQL database. I have done some comparison performance testing between Spring/Hibernate/JPA and pure JDBC. I have found a significant difference in performance using HSQL.. With Spring/Hib/JPA, I can insert 3000-4000 of my 1.5 KB objects (with a One-Many and a Many-Many relationship) in 5 seconds, while with direct JDBC calls I can insert 10,000-12,000 of those same objects. I cannot figure out why there is such a huge discrepancy. I have tweaked the Spring/Hib/JPA settings a lot trying to get close in performance without luck. I want to use Spring/Hib/JPA for future purposes, expandability, and because the foreign key relationships (one-many and many-many) are difficult to maintain by hand; but the performance requirements seem to point towards using pure JDBC. Any ideas of why there would be such a huge discrepancy?

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• Need help trying to diagnose Symmetrix SAN performance issues

  - by arcain

  I am helping to benchmark hardware for a new SQL Server instance, and the volume presented to the OS for the data files is carved from a set of spindles on a Symmetrix SAN. The server has yet to have SQL Server installed, so the only activity on the box is our benchmarking. Now, our storage engineers say that this volume and it's resources are dedicated to our new server (I don't have access to see the actual SAN config) however the performance benchmarks are troubling. For example, the numbers look good until suddenly, and randomly, we see in our IO benchmarking tool wait times of 100 seconds, and disk queue lengths of 255 in perfmon. This SAN has an 8 GB cache, plus there are other applications besides ours that use the SAN. I'm wondering if (even though the spindles for our volumes should be dedicated to us) the cache may be getting hammered during the performance testing, or perhaps the spindles our volumes are on aren't really dedicated to us. We're not getting much traction from our storage engineers in helping us track down the problem, so if anybody has experience with diagnosing a problem like this and would like to share insights and troubleshooting methodologies, I'd appreciate it.

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• python threading and performace?

  - by kumar

  I had to do heavy I/o bound operation, i.e Parsing large files and converting from one format to other format. Initially I used to do it serially, i.e parsing one after another..! Performance was very poor ( it used take 90+ seconds). So I decided to use threading to improve the performance. I created one thread for each file. ( 4 threads) for file in file_list: t=threading.Thread(target = self.convertfile,args = file) t.start() ts.append(t) for t in ts: t.join() But for my astonishment, there is no performance improvement whatsoever. Now also it takes around 90+ seconds to complete the task. As this is I/o bound operation , I had expected to improve the performance. What am I doing wrong?

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