| From: | Andres Freund <andres(at)anarazel(dot)de> |
|---|---|
| To: | Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru> |
| Cc: | Dilip Kumar <dilipbalaut(at)gmail(dot)com>, Merlin Moncure <mmoncure(at)gmail(dot)com>, Michael Paquier <michael(dot)paquier(at)gmail(dot)com>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, YUriy Zhuravlev <u(dot)zhuravlev(at)postgrespro(dot)ru>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Move PinBuffer and UnpinBuffer to atomics |
| Date: | 2016-02-01 21:43:30 |
| Message-ID: | 20160201214330.GM8743@awork2.anarazel.de |
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| Thread: | |
| Lists: | pgsql-hackers |
On 2016-02-01 13:06:57 +0300, Alexander Korotkov wrote:
> On Mon, Feb 1, 2016 at 11:34 AM, Alexander Korotkov <
> a(dot)korotkov(at)postgrespro(dot)ru> wrote:
> >> Client Base Patch
> >> 1 19744 19382
> >> 8 125923 126395
> >> 32 313931 333351
> >> 64 387339 496830
> >> 128 306412 350610
> >>
> >> Shared Buffer= 512MB
> >> max_connections=150
> >> Scale Factor=300
> >>
> >> ./pgbench -j$ -c$ -T300 -M prepared -S postgres
> >>
> >> Client Base Patch
> >> 1 17169 16454
> >> 8 108547 105559
> >> 32 241619 262818
> >> 64 206868 233606
> >> 128 137084 217013
So, there's a small regression on low client counts. That's worth
addressing.
> Attached patch is rebased and have better comments.
> Also, there is one comment which survive since original version by Andres.
>
> /* Add exponential backoff? Should seldomly be contended tho. */
>
>
> Andres, did you mean we should twice the delay with each unsuccessful try
> to lock?
Spinning on a lock as fast as possible leads to rapid cacheline bouncing
without anybody making progress. See s_lock() in s_lock.c.
Greetings,
Andres Freund
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