Re: [HACKERS] Should we cacheline align PGXACT?
От | Alexander Korotkov |
---|---|
Тема | Re: [HACKERS] Should we cacheline align PGXACT? |
Дата | |
Msg-id | CAPpHfdtEKN0+20=dFUEwgECF8x4rL7dLD8_u_mV9149p0+bqVA@mail.gmail.com обсуждение исходный текст |
Ответ на | Re: [HACKERS] Should we cacheline align PGXACT? (Alexander Korotkov <a.korotkov@postgrespro.ru>) |
Ответы |
Re: [HACKERS] Should we cacheline align PGXACT?
(Alvaro Herrera <alvherre@2ndquadrant.com>)
|
Список | pgsql-hackers |
On Wed, Feb 15, 2017 at 11:49 AM, Alexander Korotkov <a.korotkov@postgrespro.ru> wrote:
On Mon, Feb 13, 2017 at 8:02 PM, Ashutosh Sharma <ashu.coek88@gmail.com> wrote:I too have performed benchmarking of this patch on a large machine
(with 128 CPU(s), 520GB RAM, intel x86-64 architecture) and would like
to share my observations for the same (Please note that, as I had to
reverify readings on few client counts, it did take some time for me
to share these test-results.)Great! Thank you very much for testing.Case3: Data fits in shared buffer, Read-write workload:
------------------------------------------------------------ -----------------
In this case, I could see that the tps on head and patch are very
close to each other with a small variation of (+-)3-4% which i assume
is a run-to-run variation. PFA result sheet
'results-readwrite-300-1000-SF' containing the test-results. I wouldn't say it's just a variation. It looks like relatively small but noticeable regression in the patch.According to Andres comment [1] I made a version of patch (pgxact-align-3.patch) which align PGXACT to 16 bytes.That excludes situation when single PGXACT is spread over 2 cache lines.Results of read-only tests are attached. We can see that 16-byte alignment gives speedup in read-only tests, but it's a bit less than speedup of cache line alignment version.Read-write tests are now running. Hopefully 16-byte alignment version of patch wouldn't cause regression in read-write benchmark.
RW-benchmark on 72-cores machine is completed.
+-----------+--------+-------- +--------+--------+--------+-- ------+--------+--------+----- ---+
| | master | pgxact-align-2 | pgxact-align-3 |
| clients | 1 | 2 | 3 | 1 | 2 | 3 | 1 | 2 | 3 |
|-----------+--------+-------- +--------+--------+--------+-- ------+--------+--------+----- ---|
| 1 | 4696 | 4773 | 4777 | 4449 | 4766 | 4731 | 4658 | 4670 | 4807 |
| 2 | 9127 | 9154 | 9300 | 9224 | 8801 | 9055 | 9278 | 9245 | 8902 |
| 4 | 17377 | 17779 | 17740 | 17936 | 17560 | 17900 | 17806 | 17782 | 17934 |
| 8 | 34348 | 34233 | 34656 | 34204 | 33617 | 34226 | 34446 | 34105 | 34554 |
| 16 | 64350 | 64530 | 64574 | 63474 | 62852 | 63622 | 63942 | 62268 | 63396 |
| 20 | 76648 | 76515 | 75026 | 75123 | 74624 | 76461 | 77756 | 77245 | 76263 |
| 40 | 98566 | 100429 | 103499 | 103118 | 100186 | 99550 | 101489 | 102363 | 102015 |
| 60 | 106871 | 107842 | 107724 | 107168 | 107645 | 104791 | 109388 | 109367 | 106146 |
| 80 | 109461 | 108467 | 108913 | 104780 | 109742 | 106929 | 111254 | 107688 | 109581 |
| 100 | 98772 | 98641 | 94742 | 100390 | 102977 | 99691 | 99296 | 95699 | 103675 |
| 120 | 92740 | 94659 | 93876 | 91856 | 90732 | 91560 | 92334 | 88746 | 94663 |
| 140 | 88400 | 89448 | 89600 | 87173 | 90152 | 88190 | 88174 | 92784 | 91788 |
| 150 | 87292 | 92834 | 89714 | 86626 | 93090 | 88887 | 89407 | 88234 | 92760 |
| 160 | 88704 | 86890 | 87668 | 91025 | 89734 | 86875 | 88398 | 87846 | 87659 |
| 180 | 85451 | 84611 | 81913 | 86939 | 85888 | 86000 | 87287 | 85644 | 82915 |
| 200 | 73796 | 81149 | 81674 | 76179 | 73104 | 79381 | 82456 | 79920 | 76239 |
| 220 | 68113 | 69765 | 67871 | 67611 | 74125 | 66436 | 64810 | 72282 | 71387 |
| 240 | 63528 | 61462 | 65662 | 61711 | 61697 | 63032 | 65435 | 61804 | 59918 |
+-----------+--------+-------- +--------+--------+--------+-- ------+--------+--------+----- ---+
Difference between master, pgxact-align-2 and pgxact-align-3 doesn't exceed per run variation.
Thus, at this test we can't confirm neither regression in pgxact-align-2, neither improvement in pgxact-align-3.
Ashutosh, could you please repeat your benchmarks with pgxact-align-3?
The Russian Postgres Company
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