Re: Misaligned BufferDescriptors causing major performance problems on AMD

On 2015-01-05 21:43:04 -0500, Bruce Momjian wrote:
> On Fri, Jan 2, 2015 at 06:25:52PM +0100, Andres Freund wrote:
> > I can't run tests right now...
> >
> > What exactly do you want to see with these tests? that's essentially
> > what I've already benchmarked + some fprintfs?
>
> I want to test two patches that both allocate an extra 64 bytes but
> shift the alignment of just the buffer descriptor memory allocation.

pgbench scale 300, with postgres configured:
-c shared_buffers=48GB
-c log_line_prefix="[%m %p] "
-c log_min_messages=debug1
-p 5440
-c checkpoint_segments=600
-c fsync=off
-c synchronous_commit=off
-c maintenance_work_mem=4GB
-c huge_pages=off
-c log_autovacuum_min_duration='10s'

test: pgbench -n -M prepared -c 96 -j 96 -T 30 -S

master as of 4b2a254793be50e31d43d4bfd813da8d141494b8:
-c max_connections=400
tps = 193748.454044 (high run vs. run variability)
-c max_connections=401
tps = 484238.551349

master + 32align.patch:
-c max_connections=400
tps = 183791.872359 (high run vs. run variability)
-c max_connections=401
tps = 185494.98244 (high run vs. run variability)

master + 64align.patch:
-c max_connections=400
tps = 489257.195570
-c max_connections=401
tps = 490496.520632

Pretty much as expected, rigth?

Greetings,

Andres Freund

--
Andres Freund http://www.2ndQuadrant.com/
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