Re: spinlock contention

On Fri, Jul 8, 2011 at 6:02 AM, Florian Pflug <fgp(at)phlo(dot)org> wrote:
>> I don't want to fiddle with your git repo, but if you attach a patch
>> that applies to the master branch I'll give it a spin if I have time.
>
> Patch attached.
>
> Beware that it needs at least GCC 4.1, otherwise it'll use a per-partition
> spin lock instead of "locked xadd" to increment the shared counters.

[ Back from vacation, catching up on email. ]

gcc version 4.4.5 (Ubuntu/Linaro 4.4.4-14ubuntu5)

pgbench -n -S -T 180 -c 32 -j 32

with lwlock-part patch:
tps = 36974.644091 (including connections establishing)

unpatched cd34647c666be867f95ef8fc0492c30356043f10:
tps = 39432.064293 (including connections establishing)

And with -c 8 -j 8:

tps = 26946.202428 (including connections establishing)
tps = 27206.507424 (including connections establishing)

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company