| From: | Andres Freund <andres(at)anarazel(dot)de> |
|---|---|
| To: | 周正中(德歌) <dege(dot)zzz(at)alibaba-inc(dot)com> |
| Cc: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, 张广舟(明虚) <guangzhou(dot)zgz(at)alibaba-inc(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>, 范孝剑(康贤) <funnyxj(dot)fxj(at)alibaba-inc(dot)com>, 曾文旌(义从) <wenjing(dot)zwj(at)alibaba-inc(dot)com>, 窦贤明(执白) <xianming(dot)dxm(at)alibaba-inc(dot)com>, 萧少聪(铁庵) <shaocong(dot)xsc(at)alibaba-inc(dot)com>, 陈新坚(惧留孙) <xinjian(dot)chen(at)alibaba-inc(dot)com> |
| Subject: | Re: 答复：[HACKERS] 答复：[HACKERS] about fsync in CLOG buffer write |
| Date: | 2015-09-08 18:28:04 |
| Message-ID: | 20150908182804.GI5084@alap3.anarazel.de |
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| Lists: | pgsql-hackers |
Hi,
On 2015-09-08 15:58:26 +0800, 周正中(德歌) wrote:
> postgres(at)digoal-> cat 7.sql
> select txid_current();
>
> postgres(at)digoal-> pgbench -M prepared -n -r -P 1 -f ./7.sql -c 1 -j 1 -T 100000
> About 32K tps.
> progress: 240.0 s, 31164.4 tps, lat 0.031 ms stddev 0.183
> progress: 241.0 s, 33243.3 tps, lat 0.029 ms stddev 0.127
So you're benchmarking how fast you can assign txids. Is that actually
something meaningful? If you have other writes interleaved you'll write
much more WAL, so there'll be checkpoints and such.
FWIW, if you measure something realistic and there's checkpoints,
there'll be fewer fsyncs if you increase the slru buffer size - as
there'll often be clean buffers due to the checkpoint having written
them out.
Greetings,
Andres Freund
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