Re: spinlock contention - Mailing list pgsql-hackers

From Florian Pflug
Subject Re: spinlock contention
Date
Msg-id DFEF4346-3BF5-44B0-99FA-C1A219576449@phlo.org
Whole thread Raw
In response to Re: spinlock contention  (Robert Haas <robertmhaas@gmail.com>)
Responses Re: spinlock contention
List pgsql-hackers
On Jun28, 2011, at 23:48 , Robert Haas wrote:
> On Tue, Jun 28, 2011 at 5:33 PM, Merlin Moncure <mmoncure@gmail.com> wrote:
>> On Tue, Jun 28, 2011 at 3:18 PM, Robert Haas <robertmhaas@gmail.com> wrote:
>>> user-32: none(1.0),atomicinc(14.4),pg_lwlock_cas(22.1),cmpxchng(41.2),pg_lwlock(588.2),spin(1264.7)
>>
>> I may not be following all this correctly, but doesn't this suggest a
>> huge potential upside for the cas based patch you posted upthread when
>> combined with your earlier patches that were bogging down on spinlock
>> contentionl?
>
> Well, you'd think so, but in fact that patch makes it slower.  Don't
> ask me why, 'cuz I dunno.  :-(

Huh? Where do you see your CAS patch being slower than unpatched LWLocks
in these results? Or are you referring to pgbench runs you made, not
to these artificial benchmarks?

best regards,
Florian Pflug




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