Re: BufferAlloc: don't take two simultaneous locks

From: Yura Sokolov <y(dot)sokolov(at)postgrespro(dot)ru>
To: Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com>
Cc: pgsql-hackers(at)lists(dot)postgresql(dot)org, michail(dot)nikolaev(at)gmail(dot)com, x4mmm(at)yandex-team(dot)ru, andres(at)anarazel(dot)de, simon(dot)riggs(at)enterprisedb(dot)com
Subject: Re: BufferAlloc: don't take two simultaneous locks
Date: 2022-03-15 15:10:08
Message-ID: a9a81ddd10abde95196dba1892ee22c1606bcddc.camel@postgrespro.ru
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В Вт, 15/03/2022 в 13:47 +0300, Yura Sokolov пишет:
> В Вт, 15/03/2022 в 16:25 +0900, Kyotaro Horiguchi пишет:
> > > I lost access to Xeon 8354H, so returned to old Xeon X5675.
> > ...
> > > Strange thing: both master and patched version has higher
> > > peak tps at X5676 at medium connections (17 or 27 clients)
> > > than in first october version [1]. But lower tps at higher
> > > connections number (>= 191 clients).
> > > I'll try to bisect on master this unfortunate change.
> >
> > The reversing of the preference order between freshly-allocation and
> > borrow-from-another-freelist might affect.
>
> `master` changed its behaviour as well.
> It is not problem of the patch at all.

Looks like there is no issue: old commmit 2d44dee0281a1abf
behaves similar to new one at the moment.

I think, something changed in environment.
I remember there were maintanance downtime in the autumn.
Perhaps kernel were updated or some sysctl tuning changed.

----

regards
Yura.

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