| From: | Thom Brown <thom(at)linux(dot)com> |
|---|---|
| To: | Dmitry Dolgov <9erthalion6(at)gmail(dot)com> |
| Cc: | Ashutosh Bapat <ashutosh(dot)bapat(dot)oss(at)gmail(dot)com>, Tomas Vondra <tomas(at)vondra(dot)me>, Thomas Munro <thomas(dot)munro(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, Jack Ng <Jack(dot)Ng(at)huawei(dot)com>, Ni Ku <jakkuniku(at)gmail(dot)com> |
| Subject: | Re: Changing shared_buffers without restart |
| Date: | 2025-07-14 09:24:50 |
| Message-ID: | CAA-aLv7p=9jCy_-67+Wj2vrRL1QCV-X0ZFZmpAxBJqLPp-ho+A@mail.gmail.com |
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On Mon, 14 Jul 2025, 09:54 Dmitry Dolgov, <9erthalion6(at)gmail(dot)com> wrote:
> > On Mon, Jul 14, 2025 at 01:55:39PM +0530, Ashutosh Bapat wrote:
> > > You're right of course, a buffer id could be returned from the
> > > ClockSweep and from the custom strategy buffer ring. Buf from what I
> see
> > > those are picking a buffer from the set of already utilized buffers,
> > > meaning that for a buffer to land there it first has to go through
> > > StrategyControl->firstFreeBuffer, and hence the idea above will be a
> > > requirement for those as well.
> >
> > That isn't true. A buffer which was never in the free list can still
> > be picked up by clock sweep.
>
> How's that?
>
Isn't it its job to find usable buffers from the used buffer list when no
free ones are available? The next victim buffer can be selected (and
cleaned if dirty) and then immediately used without touching the free list.
Thom
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