| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
| Cc: | Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>, maryedie(at)osdl(dot)org, pgsql-hackers(at)postgresql(dot)org, Mark Wong <markw(at)osdl(dot)org>, Josh Berkus <josh(at)agliodbs(dot)com> |
| Subject: | Re: data on devel code perf dip |
| Date: | 2005-08-12 02:09:19 |
| Message-ID: | 11853.1123812559@sss.pgh.pa.us |
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| Lists: | pgsql-hackers pgsql-patches |
Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
>> O_DIRECT is only being used for WAL page writes (or I sure hope so
>> anyway), so shared_buffers should be irrelevant.
> Uh, O_DIRECT really just enables when open_sync is used, and I assume
> that is not used for writing dirty buffers during a checkpoint.
I double-checked that O_DIRECT is really just used for WAL, and only
when the sync mode is open_sync or open_datasync. So it seems
impossible that it affected a run with mode fdatasync. What seems the
best theory at the moment is that the grouped-WAL-write part of the
patch doesn't work so well as we thought.
regards, tom lane
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