| From: | Dmitry Dolgov <9erthalion6(at)gmail(dot)com> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | Thom Brown <thom(at)linux(dot)com>, 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 13:20:03 |
| Message-ID: | vslqe4duatd5hp4cw6eom3il5umpfrixylmpoh2ar27x3rstel@iengs2ijyflq |
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| Lists: | pgsql-hackers |
> On Mon, Jul 14, 2025 at 09:14:26AM -0400, Andres Freund wrote:
> > > Clock sweep can find any buffer, independent of whether it's on the freelist.
> >
> > It does the search based on nextVictimBuffer, where the actual buffer
> > will be a modulo of NBuffers, right? If that's correct and I get
> > everything else right, that would mean as long as NBuffers stays the
> > same (which is the case for the purposes of the current discussion) new
> > buffers, allocated on top of NBuffers after shared memory increase, will
> > not be picked by the clock sweep.
>
> Are you tell me that you'd put "new" buffers onto the freelist, before you
> increase NBuffers? That doesn't make sense.
Why?
> Orthogonaly - there's discussion about simply removing the freelist.
Good to know, will take a look at that thread, thanks.
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