Re[2]: [PERFORM] Re[2]: [PERFORM] SMP on a heavy loaded database

Пятница, 4 января 2013, 9:47 -05:00 от Charles Gomes <charlesrg(at)outlook(dot)com>:
>________________________________
>> From: devnull(at)mail(dot)ua
>> To: pgsql-performance(at)postgresql(dot)org
>> Subject: [PERFORM] Re[2]: [PERFORM] SMP on a heavy loaded database
>> Date: Fri, 4 Jan 2013 18:41:25 +0400
>>
>>
>>
>>
>> Пятница, 4 января 2013, 0:42 -07:00 от Scott Marlowe
>> < scott(dot)marlowe(at)gmail(dot)com >:
>> On Thu, Jan 3, 2013 at 4:45 PM, nobody nowhere
>> <devnull(at)mail(dot)ua< http://sentmsg?compose&To=devnull%40mail.ua >> wrote:
>> > Centos 5.X kernel 2.6.18-274
>> > pgsql-9.1 from pgdg-91-centos.repo
>> > relatively small database 3.2Gb
>> > Lot of insert, update, delete.
>> >
>> > I see non balanced _User_ usage on 14 CPU, exclusively assigned to
>> the hardware raid controller.
>> > What I'm doing wrong, and is it possible somehow to fix?
>> >
>> > Thanks in advance.
>> >
>> > Andrew.
>> >
>> > # top -d 10.00 -b -n 2 -U postgres -c
>> >
>> > top - 23:18:19 up 453 days, 57 min, 3 users, load average: 0.55, 0.47, 0.42
>> > Tasks: 453 total, 1 running, 452 sleeping, 0 stopped, 0 zombie
>> > Cpu0 : 0.6%us, 0.1%sy, 0.0%ni, 99.3%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
>> > Cpu1 : 0.0%us, 0.0%sy, 0.0%ni,100.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
>> > Cpu2 : 0.0%us, 0.0%sy, 0.0%ni,100.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
>> > Cpu3 : 1.2%us, 0.1%sy, 0.0%ni, 98.7%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
>> > Cpu4 : 2.6%us, 0.4%sy, 0.0%ni, 96.8%id, 0.0%wa, 0.0%hi, 0.2%si, 0.0%st
>> > Cpu5 : 0.8%us, 0.0%sy, 0.0%ni, 99.2%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
>> > Cpu6 : 5.4%us, 0.2%sy, 0.0%ni, 94.2%id, 0.2%wa, 0.0%hi, 0.0%si, 0.0%st
>> > Cpu7 : 3.3%us, 0.4%sy, 0.0%ni, 96.1%id, 0.0%wa, 0.0%hi, 0.2%si, 0.0%st
>> > Cpu8 : 1.4%us, 0.3%sy, 0.0%ni, 98.2%id, 0.0%wa, 0.0%hi, 0.1%si, 0.0%st
>> > Cpu9 : 0.0%us, 0.1%sy, 0.0%ni, 99.9%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
>> > Cpu10 : 0.0%us, 0.1%sy, 0.0%ni, 99.9%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
>> > Cpu11 : 1.6%us, 0.6%sy, 0.0%ni, 97.4%id, 0.0%wa, 0.0%hi, 0.4%si, 0.0%st
>> > Cpu12 : 0.5%us, 0.1%sy, 0.0%ni, 99.4%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
>> > Cpu13 : 1.4%us, 0.2%sy, 0.0%ni, 98.4%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
>> > Cpu14 : 24.2%us, 0.8%sy, 0.0%ni, 74.5%id, 0.3%wa, 0.0%hi, 0.2%si, 0.0%st
>> > Cpu15 : 0.7%us, 0.1%sy, 0.0%ni, 99.0%id, 0.0%wa, 0.1%hi, 0.1%si, 0.0%st
>> > Mem: 16426540k total, 16356772k used, 69768k free, 215764k buffers
>> > Swap: 4194232k total, 145280k used, 4048952k free, 14434356k cached
>> >
>>
>> So how many concurrent users are accessing this db? pgsql assigns one
>> process on one core so to speak. It can't spread load for one user
>> over all cores.
>> 64 php Fast-cgi processes over the Unix socket and about 20-30 over tcp
>
>Are you running IRQ Balance ? The OS can pin process to the respective IRQ handler. I switch off IRQ Balance on any heavy loaded servers and statically assign IRQ's to processors using
echo 000X > /proc/irq/XX/smp_affinity

irqballance do not help to fix it..