Re: Improve lseek scalability v3

From: Andres Freund
Date: Fri Sep 16 2011 - 10:41:10 EST


On Friday 16 Sep 2011 16:23:19 Andi Kleen wrote:
> > I sent an email containing benchmarks from Robert Haas regarding the
> > Subject. Looking at lkml.org I can't see it right now, Will recheck when
> > I am at home.
> I never saw that.
Hm. Not good. I see message in my imap folder marked as replied. I don't keep
mail-server logs that long though...

> Thanks for the data.
Thats Roberts work though.

> > You likely won't be able to see the bottlenecks with any of the released
> > postgres versions as there are bottlenecks fixed in HEAD that throttle
> > way before that.
> FWIW we did some postgres testing on a 4 socket, but only with the heavily
> patched MOSBENCH version, which fixes various locking problems. Didn't run
> it with that patchkit though.
I don't really now what MOSBENCH changed but I think some of the fixes Robert
are unlikely to be contained in there because they are more than just a rework
of locking itself but algorithmic changes on another level.
(Should it interest you its its likely to be
84e37126770dd6de903dad88ce150a49b63b5ef9,
b4fbe392f8ff6ff1a66b488eb7197eef9e1770a4,
3cba8999b343648c4c528432ab3d51400194e93b
8e5ac74c1249820ca55481223a95b9124b4a4f95, ...)

I also think youre only likely to notice those problems if youre running a
readonly test. The write-path is currently far to slow to see problems in that
area.

Greetings,

Andres
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