Re: MultiXact\SLRU buffers configuration

From: Thomas Munro <thomas(dot)munro(at)gmail(dot)com>
To: Andrey Borodin <x4mmm(at)yandex-team(dot)ru>
Cc: Gilles Darold <gilles(at)darold(dot)net>, Tomas Vondra <tomas(dot)vondra(at)enterprisedb(dot)com>, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, Alexander Korotkov <aekorotkov(at)gmail(dot)com>, Anastasia Lubennikova <a(dot)lubennikova(at)postgrespro(dot)ru>, Daniel Gustafsson <daniel(at)yesql(dot)se>, Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: MultiXact\SLRU buffers configuration
Date: 2021-03-25 01:03:38
Message-ID: CA+hUKGK2bkx91=CWRuPqWdXAu2JSS0mDPBh8DNuSeKhy8eOLgg@mail.gmail.com
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On Thu, Mar 25, 2021 at 10:31 AM Thomas Munro <thomas(dot)munro(at)gmail(dot)com> wrote:
> We already know that increasing the number of CLOG buffers above the
> current number hurts as the linear search begins to dominate
> (according to the commit message for 5364b357), and it doesn't seem
> great to ship a new feature that melts your CPU when you turn it up.
> Perhaps, to ship this, we need to introduce a buffer mapping table? I
> have attached a "one coffee" attempt at that, on top of your v10 patch
> (unmodified), for discussion. It survives basic testing but I don't
> know how it performs.

Hrrr... Cfbot showed an assertion failure. Here's the two coffee
version with a couple of silly mistakes fixed.

Attachment Content-Type Size
v11-0001-Make-all-SLRU-buffer-sizes-configurable.patch text/x-patch 19.5 KB
v11-0002-Add-buffer-mapping-table-for-SLRUs.patch text/x-patch 7.0 KB

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