Re: Move PinBuffer and UnpinBuffer to atomics
| От | Alexander Korotkov |
|---|---|
| Тема | Re: Move PinBuffer and UnpinBuffer to atomics |
| Дата | |
| Msg-id | CAPpHfdt1R=VF5k9fVG19GZZOQ3_HPuM9jCnM8vjJWgM7fbq2fQ@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: Move PinBuffer and UnpinBuffer to atomics (Andres Freund <andres@anarazel.de>) |
| Ответы |
Re: Move PinBuffer and UnpinBuffer to atomics
|
| Список | pgsql-hackers |
Hi!
On Fri, Oct 30, 2015 at 5:12 PM, Andres Freund <andres@anarazel.de> wrote:
------
Alexander Korotkov
Postgres Professional: http://www.postgrespro.com
On 2015-10-30 16:28:22 +0300, Alexander Korotkov wrote:
> pinunpin-cas-original-fix.patch is just original patch by Andres Freund
> with fixed bug which causes hang.
> Performance comparison on 72-cores Intel server in attached. On this
> machine we see no regression in version of patch in previous letter.
So pinunpin-cas-original-fix is my version with a bug fixed, and
pinunpin-cas is what exactly? Your earlier version with the xadd +
cmpxchg?
pinunpin-cas is still just cmpxchg with no xadd. It contain just minor changes:
Refactored version of atomic state patch is attached. The changes are following:
1) Macros are used for access refcount and usagecount.
2) likely/unlikely were removed. I think introducing of likely/unlikely should be a separate patch since it touches portability. Also, I didn't see any performance effect of this.
3) LockBufHdr returns the state after taking lock. Without using atomic increments it still can save some loops on skip atomic value reading.
I compare them just to show there is no regression because of these changes.
The results look pretty good. Could you give a few more details about
the hardware and workload (i.e. cpu model number + scale)?
It is 4 socket Intel(R) Xeon(R) CPU E7-8890 v3 @ 2.50GHz, 2 Tb of memory, all data in shared_buffers, 1000 scale factor, -M prepared, pgbench runs on the same maching through unix socket.
So the plan would be to finish cleaning this up into a committable
shape?
Yes.
Alexander Korotkov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company
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