From: | Ashutosh Sharma <ashu(dot)coek88(at)gmail(dot)com> |
---|---|
To: | Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr> |
Cc: | Andres Freund <andres(at)anarazel(dot)de>, Robert Haas <robertmhaas(at)gmail(dot)com>, Mithun Cy <mithun(dot)cy(at)enterprisedb(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> |
Subject: | Re: Perf Benchmarking and regression. |
Date: | 2016-05-27 04:29:51 |
Message-ID: | CAE9k0P=331fQ49AMscm+N9K03avWhMKpEi4RN=jgmF_GB87Ewg@mail.gmail.com |
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Lists: | pgsql-hackers |
Hi All,
As we have seen the regression of more than 45% with "*backend_flush_after*"
enabled and set to its default value i.e. 128KB or even when it is set to
some higher value like 2MB, i think we should disable it such that it does
not impact the read write performance and here is the attached patch for
the same. Please have a look and let me know your thoughts on this. Thanks!
With Regards,
Ashutosh Sharma
EnterpriseDB: http://www.enterprisedb.com
On Sun, May 15, 2016 at 1:26 AM, Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr> wrote:
>
> These raw tps suggest that {backend,bgwriter}_flush_after should better be
>>> zero for this kind of load.Whether it should be the default is unclear
>>> yet,
>>> because as Andres pointed out this is one kind of load.
>>>
>>
>> FWIW, I don't think {backend,bgwriter} are the same here. It's primarily
>> backend that matters.
>>
>
> Indeed, I was a little hasty to put bgwriter together based on this report.
>
> I'm a little wary of "bgwriter_flush_after" though, I would not be
> surprised if someone reports some regressions, although probably not with a
> pgbench tpcb kind of load.
>
> --
> Fabien.
>
Attachment | Content-Type | Size |
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disable-guc-var-backend_flush_after-by-default.patch | text/plain | 527 bytes |
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