From: | Fujii Masao <masao(dot)fujii(at)oss(dot)nttdata(dot)com> |
---|---|
To: | Thomas Munro <thomas(dot)munro(at)gmail(dot)com>, Michael Brown <michael(dot)brown(at)discourse(dot)org> |
Cc: | pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: fdatasync performance problem with large number of DB files |
Date: | 2021-03-11 01:00:37 |
Message-ID: | cfc60fae-dfac-eb49-4bab-9e90bc633588@oss.nttdata.com |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-hackers |
On 2021/03/11 8:30, Thomas Munro wrote:
> On Thu, Mar 11, 2021 at 11:38 AM Thomas Munro <thomas(dot)munro(at)gmail(dot)com> wrote:
>> On Thu, Mar 11, 2021 at 11:01 AM Michael Brown
>> <michael(dot)brown(at)discourse(dot)org> wrote:
>>> * is there a knob missing we can configure?
>>> * can we get an opt-in knob to use a single sync() call instead of a
>>> recursive fsync()?
>>> * would you be open to merging a patch providing said knob?
>>> * is there something else we missed?
>>
>> As discussed on that other thread, I don't think sync() is an option
>> (it doesn't wait on all OSes or in the standard and it doesn't report
>> errors). syncfs() on Linux 5.8+ looks like a good candidate though,
>> and I think we'd consider a patch like that. I mean, I even posted
>> one[1] in that other thread. There will of course be cases where
>> that's slower (small database sharing filesystem with other software
>> that has a lot of dirty data to write back).
>
> Thinking about this some more, if you were to propose a patch like
> that syncfs() one but make it a configurable option, I'd personally be
> in favour of trying to squeeze it into v14. Others might object on
> commitfest procedural grounds, I dunno, but I think this is a real
> operational issue and that's a fairly simple and localised change.
+1 to push this kind of change into v14!!
> I've run into a couple of users who have just commented that recursive
> fsync() code out!
BTW, we can skip that recursive fsync() by disabling fsync GUC even without
commenting out the code?
Regards,
--
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION
From | Date | Subject | |
---|---|---|---|
Next Message | Masahiko Sawada | 2021-03-11 01:01:21 | Re: Boundary value check in lazy_tid_reaped() |
Previous Message | Bruce Momjian | 2021-03-11 00:58:39 | Re: pgbench - add pseudo-random permutation function |