Re: Speed up Clog Access by increasing CLOG buffers

On Mon, Dec 5, 2016 at 6:00 AM, Haribabu Kommi <kommi(dot)haribabu(at)gmail(dot)com> wrote:
>
>
> On Fri, Nov 4, 2016 at 8:20 PM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>>
>> On Thu, Nov 3, 2016 at 8:38 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>> > On Tue, Nov 1, 2016 at 11:31 PM, Tomas Vondra
>> >> The difference is that both the fast-path locks and msgNumLock went
>> >> into
>> >> 9.2, so that end users probably never saw that regression. But we don't
>> >> know
>> >> if that happens for clog and WAL.
>> >>
>> >> Perhaps you have a working patch addressing the WAL contention, so that
>> >> we
>> >> could see how that changes the results?
>> >
>> > I don't think we do, yet.
>> >
>>
>> Right. At this stage, we are just evaluating the ways (basic idea is
>> to split the OS writes and Flush requests in separate locks) to reduce
>> it. It is difficult to speculate results at this stage. I think
>> after spending some more time (probably few weeks), we will be in
>> position to share our findings.
>>
>
> As per my understanding the current state of the patch is waiting for the
> performance results from author.
>

No, that is not true. You have quoted the wrong message, that
discussion was about WALWriteLock contention not about the patch being
discussed in this thread. I have posted the latest set of patches
here [1]. Tomas is supposed to share the results of his tests. He
mentioned to me in PGConf Asia last week that he ran few tests on
Power Box, so let us wait for him to share his findings.

> Moved to next CF with "waiting on author" status. Please feel free to
> update the status if the current status differs with the actual patch
> status.
>

I think we should keep the status as "Needs Review".

[1] - https://www.postgresql.org/message-id/CAA4eK1JjatUZu0%2BHCi%3D5VM1q-hFgN_OhegPAwEUJqxf-7pESbg%40mail.gmail.com

--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com