Re: Performance degradation in commit 6150a1b0

On 2016-03-25 09:29:34 +0530, Amit Kapila wrote:
> > 2. Secondly, i can see that the BufferDesc structure padding is 64 bytes
> however the PG CACHE LINE ALIGNMENT is 128 bytes. Also, after changing the
> BufferDesc structure padding size to 128 bytes along with the changes
> mentioned in above point #1, I see that the overall performance is again
> similar to what is observed before commit 6150a1b0.

That makes sense, as it restores alignment.

> So this indicates that changing back content lock as LWLock* in BufferDesc
> brings back the performance which indicates that increase in BufferDesc
> size to more than 64bytes on this platform has caused regression.  I think
> it is worth trying the patch [1] as suggested by Andres as that will reduce
> the size of BufferDesc which can bring back the performance.  Can you once
> try the same?
> 
> [1] -
> http://www.postgresql.org/message-id/CAPpHfdsRoT1JmsnRnCCqpNZEU9vUT7TX6B-N1wyOuWWfhD6F+g@mail.gmail.com

Yes please. I'll try to review that once more ASAP.


Regards,

Andres