| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Stefan Kaltenbrunner <stefan(at)kaltenbrunner(dot)cc> |
| Cc: | Andrew Dunstan <andrew(at)dunslane(dot)net>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: lock contention on parallel COPY ? |
| Date: | 2008-09-26 16:38:14 |
| Message-ID: | 19475.1222447094@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Stefan Kaltenbrunner <stefan(at)kaltenbrunner(dot)cc> writes:
> heh no log archiving - I actually said that I'm now playing with
> --truncate-before-load which seems to cause a noticeable performance (as
> in IO generated) increase but I still see >130000 context switches/s and
> a profile that looks like:
> samples % symbol name
> 55526 16.5614 LWLockAcquire
> 29721 8.8647 DoCopy
> 26581 7.9281 CopyReadLine
> 25105 7.4879 LWLockRelease
> 15743 4.6956 PinBuffer
> 14725 4.3919 heap_formtuple
Still a lot of contention for something, then. You might try turning on
LWLOCK_STATS (this only requires recompiling storage/lmgr/lwlock.c) to
get some evidence about what.
regards, tom lane
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