From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | Jakub Ouhrabka <kuba(at)comgate(dot)cz> |
Cc: | pgsql-performance(at)postgresql(dot)org |
Subject: | Re: Linux/PostgreSQL scalability issue - problem with 8 cores |
Date: | 2008-01-03 16:59:30 |
Message-ID: | 7083.1199379570@sss.pgh.pa.us |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-performance |
Jakub Ouhrabka <kuba(at)comgate(dot)cz> writes:
> we have a PostgreSQL dedicated Linux server with 8 cores (2xX5355). We
> came accross a strange issue: when running with all 8 cores enabled
> approximatly once a minute (period differs) the system is very busy for
> a few seconds (~5-10s) and we don't know why - this issue don't show up
> when we tell Linux to use only 2 cores, with 4 cores the problem is here
> but it is still better than with 8 cores - all on the same machine, same
> config, same workload. We don't see any apparent reason for these peaks.
Interesting. Maybe you could use oprofile to try to see what's
happening? It sounds a bit like momentary contention for a spinlock,
but exactly what isn't clear.
> Can this be connected with our heavy use of listen/notify and hundreds
> backends in listen mode?
Perhaps. Have you tried logging executions of NOTIFY to see if they are
correlated with the spikes?
regards, tom lane
From | Date | Subject | |
---|---|---|---|
Next Message | Jakub Ouhrabka | 2008-01-03 17:37:29 | Re: Linux/PostgreSQL scalability issue - problem with 8 cores |
Previous Message | Tom Lane | 2008-01-03 16:35:01 | Re: Commit takes a long time. |