----- "Claudio Freire" <klaussfreire@xxxxxxxxx> wrote: | From: "Claudio Freire" <klaussfreire@xxxxxxxxx> | To: "Rajesh Kumar. Mallah" <mallah@xxxxxxxxxxxxxx> | Cc: pgsql-performance@xxxxxxxxxxxxxx | Sent: Thursday, May 24, 2012 9:23:43 AM | Subject: Re: High load average in 64-core server , no I/O wait and CPU is idle | | On Thu, May 24, 2012 at 12:39 AM, Rajesh Kumar. Mallah | <mallah@xxxxxxxxxxxxxx> wrote: | > The problem is that sometimes there are spikes of load avg which | > jumps to > 50 very rapidly ( ie from 0.5 to 50 within 10 secs) and | > it remains there for sometime and slowly reduces to normal value. | > | > During such times of high load average we observe that there is no | IO wait | > in system and even CPU is 50% idle. In any case the IO Wait always | remains < 1.0 % and | > is mostly 0. Hence the load is not due to high I/O wait which was | generally | > the case with our previous hardware. | | Do you experience decreased query performance? Yes we do experience substantial application performance degradations. | | Load can easily get to 64 (1 per core) without reaching its capacity. | So, unless you're experiencing decreased performance I wouldn't think | much of it. I far as i understand , Load Avg is the average number of processes waiting to be run in past 1 , 5 or 15 mins. A number > 1 would mean that countable number of processes were waiting to be run. how can load of more than 1 and upto 64 be OK for a 64 core machine ? | | Do you have mcelog running? as a cron or a daemon? No we do not have mcelog. BTW the Postgresql version is : 9.1.3 which i forgot to mention in my last email. regds mallah. | Sometimes, mcelog tends to crash in that way. We had to disable it in | our servers because it misbehaved like that. It only makes load avg | meaningless, no performance impact, but being unable to accurately | measure load is bad enough. -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
