From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | "Hiroshi Inoue" <Inoue(at)tpf(dot)co(dot)jp> |
Cc: | "Schmidt, Peter" <peter(dot)schmidt(at)prismedia(dot)com>, pgsql-hackers(at)postgresql(dot)org, pgsql-admin(at)postgresql(dot)org |
Subject: | Re: [HACKERS] Re: v7.1b4 bad performance |
Date: | 2001-02-20 21:52:43 |
Message-ID: | 6776.982705963@sss.pgh.pa.us |
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"Hiroshi Inoue" <Inoue(at)tpf(dot)co(dot)jp> writes:
>> Hmm, you mean you set up a separate test database for each pgbench
>> "client", but all under the same postmaster?
> Yes. Different database is to make the conflict as less as possible.
> The conflict among backends is a greatest enemy of CommitDelay.
Okay, so this errs in the opposite direction from the original form of
the benchmark: there will be *no* cross-backend locking delays, except
for accesses to the common WAL log. That's good as a comparison point,
but we shouldn't trust it absolutely either.
>> What platform is this on --- in particular, how long a delay
>> is CommitDelay=1 in reality? What -B did you use?
> platform) i686-pc-linux-gnu, compiled by GCC egcs-2.91.60(turbolinux 4.2)
> min delay) 10msec according to your test program.
> -B) 64 (all other settings are default)
Thanks. Could I trouble you to run it again with a larger -B, say
1024 or 2048? What I've found is that at -B 64, the benchmark is
so constrained by limited buffer space that it doesn't reflect
performance at a more realistic production setting.
regards, tom lane
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