On 2016-02-01 13:06:57 +0300, Alexander Korotkov wrote:
> On Mon, Feb 1, 2016 at 11:34 AM, Alexander Korotkov <
> a.korotkov@postgrespro.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
