| From: | Stefan Kaltenbrunner <stefan(at)kaltenbrunner(dot)cc> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | "Joshua D(dot) Drake" <jd(at)commandprompt(dot)com>, Luke Lonergan <llonergan(at)greenplum(dot)com>, Greg Smith <gsmith(at)gregsmith(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: 8.3 / 8.2.6 restore comparison |
| Date: | 2008-02-23 17:53:19 |
| Message-ID: | 47C05D8F.1000104@kaltenbrunner.cc |
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| Lists: | pgsql-hackers |
Tom Lane wrote:
> "Joshua D. Drake" <jd(at)commandprompt(dot)com> writes:
>> Yeah, that... is beyond my abilities. Well reading it is anyway. I can
>> provide any information people want though. Tom? Greg? Andrew? Somebody?
>> What information do you want from me to help you track this down?
>
> The vmstat output you showed before said user CPU time was only around
> 12%, which seems to destroy Luke's thesis that data conversion time
> is the problem. IIRC we were speculating that data was being written
> in a pattern that required a lot of seeking thus ruining throughput,
> but we didn't have any hard evidence of that. Did you do the strace'ing
> I suggested?
Joshua said this is an 8 core box - so 12% would about equal to one core
being maxed out completely CPU wise which seems to correlate fairly well
with my experience (COPY being CPU bottlenecked on fast hardware without
any real culprit to find in profiles).
Stefan
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