On Sun, Nov 1, 2015 at 8:46 PM, Jim Nasby <jim.na...@bluetreble.com> wrote:
> On 5/25/15 10:04 PM, Amit Kapila wrote:
>> On Tue, May 26, 2015 at 12:10 AM, Andres Freund <and...@anarazel.de
>> <mailto:and...@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  people posting test results with such a workload
>> showing ProcArrayLock as contention.
>>  -
> Anything happen with this?
No. I think one has to study the impact of this patch on latest code
especially after commit-0e141c0f.