Re: checkpointer continuous flushing

On Thu, Dec 17, 2015 at 4:27 AM, Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr> wrote:
>
> Hello Tomas,
>
>> I'm planning to do some thorough benchmarking of the patches proposed in
>> this thread, on various types of hardware (10k SAS drives and SSDs). But is
>> that actually needed? I see Andres did some testing, as he posted summary of
>> the results on 11/12, but I don't see any actual results or even info about
>> what benchmarks were done (pgbench?).
>>
>> If yes, do we only want to compare 0001-ckpt-14-andres.patch against
>> master, or do we need to test one of the previous Fabien's patches?
>
>
> My 0.02€,
>
> Although I disagree with some aspects of Andres patch, I'm not a committer
> and I'm tired of arguing. I'm just planing to do minor changes to Andres
> version to fix a potential issue if the file is closed which flushing is in
> progress, but that will not change the overall shape of it.
>
> So testing on Andres version seems relevant to me.
>
> For SSD the performance impact should be limited. For disk it should be
> significant if there is no big cache in front of it. There were some
> concerns raised for some loads in the thread (shared memory smaller than
> needed I think?), if you can include such cases that would be great. My
> guess is that it should be not very beneficial in this case because the
> writing is mostly done by bgwriter & worker in this case, and these are
> still random.

As there are still plans to move on regarding tests (and because this
patch makes a difference), this is moved to next CF.
--
Michael