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items: Strange performance issue
items: Re: Strange performance issue

Strange performance issue
type: item
description: I've got a strange performance issue on a host machine that has a number of VPS on it but I wouldn't call overloaded and it seems to be a CPU limit issue but I can't see what On the host [root@vz26uk ~]# time perl -e 'sqrt(100) for (0..1000000)' real 0m0.044s user 0m0.041s sys 0m0.003s Inside the VE [root@vz26uk ~]# vzctl exec 881980 "time perl -e 'sqrt(100) for (0..1000000)'" real 0m3.897s user 0m3.881s sys 0m0.015s [root@vz26uk ~]# uname -a Linux vz26uk.vaserv.com 2.6.9-023stab044.4-smp #1 SMP Mon May 28 23:15:47 MSD 2007 x86_64 x86_64 x86_64 GNU/Linux [root@vz26uk ~]# uptime 16:32:49 up 5 days, 9:41, 1 user, load average: 1.37, 0.88, 0.67 CPU is Core2Quad with all 4 CPU's detected [root@vz26uk ~]# free total used free shared buffers cached Mem: 6267700 6205080 62620 0 37960 1288820 -/+ buffers/cache: 4878300 1389400 Swap: 2096472 764 2095708 Slighty editted conf file [root@vz26uk ~]# cat /etc/sysconfig/vz-scripts/881980.conf ONBOOT="yes" # UBC parameters (in form of barrier:limit) # Primary parameters AVNUMPROC="40:40" NUMPROC="999999:999999" NUMTCPSOCK="7999992:7999992" NUMOTHERSOCK="7999992:7999992" VMGUARPAGES="131072:2147483647" # Secondary parameters KMEMSIZE="2147483646:2147483646" TCPSNDBUF="107374592:289400832" TCPRCVBUF="107374592:289400832" OTHERSOCKBUF="107374592:289400832" DGRAMRCVBUF="107374592:289400832" OOMGUARPAGES="131072:2147483647" # Auxiliary parameters LOCKEDPAGES="999999:999999" SHMPAGES="131072:131072" PRIVVMPAGES="262144:262144" NUMFILE="23999976:23999976" NUMFLOCK="999999:999999" NUMPTY="500000:500000" NUMSIGINFO="999999:999999" DCACHESIZE="2147483646:2147483646" PHYSPAGES="0:2147483647" NUMIPTENT="999999:999999" # Disk quota parameters (in form of softlimit:hardlimit) DISKSPACE="20480000:20480000" DISKINODES="10240000:10240000" QUOTATIME="0" # CPU fair sheduler parameter CPUUNITS="1000" VE_ROOT="/vz/root/$VEID" VE_PRIVATE="/vz/private/881980" OSTEMPLATE="cpanel" ORIGIN_SAMPLE="vps.basic" QUOTAUGIDLIMIT="1000" CPULIMIT="400" MEMINFO="page…
creator: vaserv
date: 2007-08-20T20:40:58-00:00

Re: Strange performance issue
type: item
description: these values appear very low for your hardware CPULIMIT="400" CPUUNITS="1000" (am i correct the limit should not be smaller than the assigned units for an individual VPS?) vzcpucheck will give you your current HN limit and you will see immediately you need a sane view on your HN capability. run vzsplit on your HN and split 16 ways then again split 32 ways. compare the output and look at the CPULIMIT values also from you config it is interesting for you to look at the limits values for: VMGUARPAGES OOMGUARPAGES PRIVVMPAGES SHMPAGES EDIT: OFF TOPIC: i would also consider rebooting the HN to clear that memory logjam. and your SWAP is way too small, i would prefer it was 6GB min
creator: locutius
date: 2007-08-20T21:31:27-00:00

Re: Strange performance issue
type: item
description: Everyone has the same CPUUNITS/CPULIMIY so as I understand it everything should be equal. Just going to an extreme though [root@vz26uk ~]# vzctl set 881980 --cpulimit 10000 --cpuunits 480082 Setting CPU limit: 10000 Setting CPU units: 480082 Configure meminfo: 262144 WARNING: Settings were not saved and will be resetted to original values on next start (use --save flag) [root@vz26uk ~]# vzctl exec 881980 "time perl -e 'sqrt(100) for (0..1000000)'" real 0m2.971s user 0m2.934s sys 0m0.034s No change (BTW this node is running hypervm so those limits are set via that but I take what you are saying.) Its just this one VPS out of 700 or so that is playing up which I'm finding weird all with very similar settings
creator: vaserv
date: 2007-08-20T21:35:39-00:00

Re: Strange performance issue
type: item
description: did you try raising his AVNUMPROC? do you know what is he running? btw is hypervm any good?
creator: locutius
date: 2007-08-20T21:55:26-00:00

Re: Strange performance issue
type: item
description: I put it to 250 (average is actually 60-80) Running cPanel, no active websites From inside the VE root@ariel [/]# uptime 22:53:24 up 15:27, 0 users, load average: 0.10, 0.07, 0.02 root@ariel [/]# free total used free shared buffers cached Mem: 1048576 311112 737464 0 0 0 -/+ buffers/cache: 311112 737464 Swap: 0 0 0 root@ariel [/]# time perl -e 'sqrt(100) for (0..1000000)' real 0m3.863s user 0m3.861s sys 0m0.003s
creator: vaserv
date: 2007-08-20T21:58:49-00:00

Re: Strange performance issue
type: item
description: reboot him see if it persists (i guess you done that already)
creator: locutius
date: 2007-08-21T02:57:33-00:00

Re: Strange performance issue
type: item
description: locutius wrote on Mon, 20 August 2007 17:31 these values appear very low for your hardware CPULIMIT="400" CPUUNITS="1000" (am i correct the limit should not be smaller than the assigned units for an individual VPS?) vzcpucheck will give you your current HN limit and you will see immediately you need a sane view on your HN capability. run vzsplit on your HN and split 16 ways then again split 32 ways. compare the output and look at the CPULIMIT values also from you config it is interesting for you to look at the limits values for: VMGUARPAGES OOMGUARPAGES PRIVVMPAGES SHMPAGES EDIT: OFF TOPIC: i would also consider rebooting the HN to clear that memory logjam. and your SWAP is way too small, i would prefer it was 6GB min CPUUnits is accounted by vzcpucheck, not cpulimit. CPUlimit is 100 for every core/cpu you have. Therefore for a quad-core the maximum is 400. Try raising the cpuunits to more like 100000 instead of 1000, although I'm not sure if that will do anything.
creator: devonblzx
date: 2007-08-21T05:37:44-00:00