Re: Move PinBuffer and UnpinBuffer to atomics

On Sun, Mar 27, 2016 at 4:31 PM, Alexander Korotkov <
a(dot)korotkov(at)postgrespro(dot)ru> wrote:

> On Sun, Mar 27, 2016 at 3:10 PM, Andres Freund <andres(at)anarazel(dot)de> wrote:
>
>> On 2016-03-27 12:38:25 +0300, Alexander Korotkov wrote:
>> > On Sat, Mar 26, 2016 at 1:26 AM, Alexander Korotkov <
>> > a(dot)korotkov(at)postgrespro(dot)ru> wrote:
>> >
>> > > Thank you very much for testing!
>> > > I also got access to 4 x 18 Intel server with 144 threads. I'm going
>> to
>> > > post results of tests on this server in next Monday.
>> > >
>> >
>> > I've run pgbench tests on this machine: pgbench -s 1000 -c $clients -j
>> 100
>> > -M prepared -T 300.
>> > See results in the table and chart.
>> >
>> > clients master v3 v5
>> > 1 11671 12507 12679
>> > 2 24650 26005 25010
>> > 4 49631 48863 49811
>> > 8 96790 96441 99946
>> > 10 121275 119928 124100
>> > 20 243066 243365 246432
>> > 30 359616 342241 357310
>> > 40 431375 415310 441619
>> > 50 489991 489896 500590
>> > 60 538057 636473 554069
>> > 70 588659 714426 738535
>> > 80 405008 923039 902632
>> > 90 295443 1181247 1155918
>> > 100 258695 1323125 1325019
>> > 110 238842 1393767 1410274
>> > 120 226018 1432504 1474982
>> > 130 215102 1465459 1503241
>> > 140 206415 1470454 1505380
>> > 150 197850 1475479 1519908
>> > 160 190935 1420915 1484868
>> > 170 185835 1438965 1453128
>> > 180 182519 1416252 1453098
>> >
>> > My conclusions are following:
>> > 1) We don't observe any regression in v5 in comparison to master.
>> > 2) v5 in most of cases slightly outperforms v3.
>>
>> What commit did you base these tests on? I guess something recent, after
>> 98a64d0bd?
>>
>
> Yes, more recent than 98a64d0bd. It was based on 676265eb7b.
>
>
>> > I'm going to do some code cleanup of v5 in Monday
>>
>> Ok, I'll try to do a review and possibly commit after that.
>>
>
> Sounds good.
>

There is next revision of patch. It contains mostly cosmetic changes.
Comment are adjusted to reflect changes of behaviour.
I also changed atomic AND/OR for local buffers to read/write pair which
would be cheaper I suppose. However, I don't insist on it, and it could be
reverted.
The patch is ready for your review. It's especially interesting what do
you think about the way I abstracted exponential back off of spinlock.

------
Alexander Korotkov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company