| From: | Andres Freund <andres(at)anarazel(dot)de> |
|---|---|
| To: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> |
| Cc: | Ashutosh Sharma <ashu(dot)coek88(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Performance degradation in commit 6150a1b0 |
| Date: | 2016-03-25 07:08:41 |
| Message-ID: | 20160325070841.pcmlskg7kxpywap6@alap3.anarazel.de |
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| Lists: | pgsql-hackers |
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
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