Re: Background writer and checkpointer in crash recovery - Mailing list pgsql-hackers

From Robert Haas
Subject Re: Background writer and checkpointer in crash recovery
Date
Msg-id CA+TgmoZmXLn6SFzxmPqVx2h4Nf2SzCePCzxA-K0J9ikO2LvUCg@mail.gmail.com
Whole thread Raw
In response to Re: Background writer and checkpointer in crash recovery  (Andres Freund <andres@anarazel.de>)
Responses RE: Background writer and checkpointer in crash recovery  (Jakub Wartak <Jakub.Wartak@tomtom.com>)
List pgsql-hackers
On Fri, Jul 30, 2021 at 4:00 PM Andres Freund <andres@anarazel.de> wrote:
> I don't agree with that? If (user+system) << wall then it is very likely
> that recovery is IO bound. If system is a large percentage of wall, then
> shared buffers is likely too small (or we're replacing the wrong
> buffers) because you spend a lot of time copying data in/out of the
> kernel page cache. If user is the majority, you're CPU bound.
>
> Without user & system time it's much harder to figure that out - at
> least for me.

Oh, that's an interesting point. At least now I'll know why I am
supposed to care about that log line the next time I see it. I guess
we could include both things, though the line might get a little long.
Or maybe there's some other subset that would make sense.

-- 
Robert Haas
EDB: http://www.enterprisedb.com



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