2009/5/28 Flavio Henrique Araque Gurgel <fla...@4linux.com.br> > ----- "Scott Marlowe" <scott.marl...@gmail.com> escreveu: > > On Thu, May 28, 2009 at 12:50 PM, Fabrix <fabrix...@gmail.com> wrote: > > > > > > HI. > > > > > > Someone had some experience of bad performance with postgres in some > server > > > with many processors? > > I had. > > > > but I have experienced problems with another server that has 8 CPUS > quad > > > core (32 cores). The second one only gives me about 1.5 of performance > of > > > the first one. > > I have had problems with 4 CPUS dual core Hyper Threading (16 logical > CPUS). > > > What model CPUs and chipset on the mobo I wonder? > > > > > Monitoring (nmon, htop, vmstat) see that everything is fine (memory, > HD, > > > eth, etc) except that processors regularly climb to 100%. > > > > > > I can see that the processes are waiting for CPU time: > > > > Have postgres problems of lock or degradation of performance with many > > > CPU's? > > > Any comments? > > > > Looks like a context switch storm, which was pretty common on older > > Xeon CPUs. I imagine with enough pg processes running on enough CPUs > > it could still be a problem. > > I would ask for your kernel version. uname -a please? >
sure, and thanks for you answer Flavio... uname -a Linux SERVIDOR-A 2.6.18-92.el5 #1 SMP Tue Apr 29 13:16:15 EDT 2008 x86_64 x86_64 x86_64 GNU/Linux cat /etc/redhat-release Red Hat Enterprise Linux Server release 5.2 (Tikanga) > > It was possible to make the context work better with 2.4.24 with kswapd > patched around here. 1600 connections working fine at this moment. > 2.4 is very old, or not? > > Try to lower your memory requirements too. Linux kernel needs some space to > page and scale up. Install some more memory otherwise. > how much? already I have a lot of memory installed in the server 128GB. > Flavio > >
