| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Amit kapila <amit(dot)kapila(at)huawei(dot)com> |
| Cc: | Andres Freund <andres(at)2ndquadrant(dot)com>, Greg Smith <greg(at)2ndquadrant(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Move unused buffers to freelist |
| Date: | 2013-07-01 18:29:59 |
| Message-ID: | CA+TgmoZ7dvhC4h-ffJmZCff6VWyNfOEAPZ021VxW61uH46R3QA@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Sun, Jun 30, 2013 at 3:24 AM, Amit kapila <amit(dot)kapila(at)huawei(dot)com> wrote:
> Do you think it will be sufficient to just wake bgwriter when the buffers in freelist drops
> below low watermark, how about it's current job of flushing dirty buffers?
Well, the only point of flushing dirty buffers in the background
writer is to make sure that backends can allocate buffers quickly. If
there are clean buffers already in the freelist, that's not a concern.
So...
> I mean to ask that if for some scenario where there are sufficient buffers in freelist, but most
> other buffers are dirty, will delaying flush untill number of buffers fall below low watermark is okay.
...I think this is OK, or at least we should assume it's OK until we
have evidence that it isn't.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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