Re: Spin Lock sleep resolution

Hi David,

On 02.04.2013 22:58, David Gould wrote:
> On Tue, 2 Apr 2013 09:01:36 -0700
> Jeff Janes<jeff(dot)janes(at)gmail(dot)com> wrote:
>
>> Sorry. I triple checked that the patch was there, but it seems like if you
>> save a draft with an attachment, when you come back later to finish and
>> send it, the attachment may not be there anymore. The Gmail Offline teams
>> still has a ways to go. Hopefully it is actually there this time.
>
> I'll give the patch a try, I have a workload that is impacted by spinlocks
> fairly heavily sometimes and this might help or at least give me more
> information. Thanks!

Did you ever get around to test this?

I repeated these pgbench tests I did earlier:

http://www.postgresql.org/message-id/5190E17B.9060804@vmware.com

I concluded in that thread that on this platform, the TAS_SPIN macro
really needs a non-locked test before the locked one. That fixes the big
fall in performance with more than 28 clients. So I repeated that test
with four versions:

master - no patch
spin-delay-ms - Jeff's patch
nonlocked-test - master with the non-locked test added to TAS_SPIN
spin-delay-ms-nonlocked-test - both patches

Jeff's patch seems to somewhat alleviate the huge fall in performance
I'm otherwise seeing without the nonlocked-test patch. With the
nonlocked-test patch, if you squint you can see a miniscule benefit.

I wasn't expecting much of a gain from this, just wanted to verify that
it's not making things worse. So looks good to me.

- Heikki