Re: POC: Cache data in GetSnapshotData()

On 5/25/15 10:04 PM, Amit Kapila wrote:
> On Tue, May 26, 2015 at 12:10 AM, Andres Freund <andres@anarazel.de
> <mailto:andres@anarazel.de>> wrote:
>  >
>  > On 2015-05-20 19:56:39 +0530, Amit Kapila wrote:
>  > > I have done some tests with this patch to see the benefit with
>  > > and it seems to me this patch helps in reducing the contention
>  > > around ProcArrayLock, though the increase in TPS (in tpc-b tests
>  > > is around 2~4%) is not very high.
>  > >
>  > > pgbench (TPC-B test)
>  > > ./pgbench -c 64 -j 64 -T 1200 -M prepared postgres
>  >
>  > Hm, so it's a read mostly test.
>
> Write not *Read* mostly.
>
>  > I probably not that badly contended on
>  > the snapshot acquisition itself. I'd guess a 80/20 read/write mix or so
>  > would be more interesting for the cases where we hit this really bad.
>  >
>
> Yes 80/20 read/write mix will be good test to test this patch and I think
> such a load is used by many applications (Such a load is quite common
> in telecom especially their billing related applications) and currently
> we don't
> have such a test handy to measure performance.
>
> On a side note, I think it would be good if we can add such a test to
> pgbench or may be use some test which adheres to TPC-C specification.
> Infact, I remember [1] people posting test results with such a workload
> showing ProcArrayLock as contention.
>
>
> [1] -
> http://www.postgresql.org/message-id/E8870A2F6A4B1045B1C292B77EAB207C77069A80@SZXEMA501-MBX.china.huawei.com

Anything happen with this?
-- 
Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX
Experts in Analytics, Data Architecture and PostgreSQL
Data in Trouble? Get it in Treble! http://BlueTreble.com