| From: | Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru> |
|---|---|
| To: | Dilip Kumar <dilipbalaut(at)gmail(dot)com> |
| Cc: | Andres Freund <andres(at)anarazel(dot)de>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Ashutosh Sharma <ashu(dot)coek88(at)gmail(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Merlin Moncure <mmoncure(at)gmail(dot)com>, Michael Paquier <michael(dot)paquier(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: | 2016-04-05 14:36:49 |
| Message-ID: | CAPpHfdvcQnPQU3_KwQHNmngsQFfihx6b21KsW6LACnHhoXW_bQ@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Tue, Apr 5, 2016 at 10:26 AM, Dilip Kumar <dilipbalaut(at)gmail(dot)com> wrote:
>
> On Mon, Apr 4, 2016 at 2:28 PM, Andres Freund <andres(at)anarazel(dot)de> wrote:
>
>> Hm, interesting. I suspect that's because of the missing backoff in my
>> experimental patch. If you apply the attached patch ontop of that
>> (requires infrastructure from pinunpin), how does performance develop?
>>
>
> I have applied this patch also, but still results are same, I mean around
> 550,000 with 64 threads and 650,000 with 128 client with lot of
> fluctuations..
>
> *128 client **(head+**0001-WIP-Avoid-the-use-of-a-separate-spinlock-to-protect
> +pinunpin-cas-9+backoff)*
>
> run1 645769
> run2 643161
> run3 *285546*
> run4 *289421*
> run5 630772
> run6 *284363*
>
Could the reason be that we're increasing concurrency for LWLock state
atomic variable by placing queue spinlock there?
But I wonder why this could happen during "pgbench -S", because it doesn't
seem to have high traffic of exclusive LWLocks.
------
Alexander Korotkov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company
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