MySQL Bugs: #59788: Multiple buffer pool instances: small performance gain <8 serious degradation >8

Bug #59788	Multiple buffer pool instances: small performance gain <8 serious degradation >8
Submitted:	28 Jan 2011 1:33	Modified:	27 Feb 2017 5:34
Reporter:	Roel Van de Paar	Email Updates:
Status:	Not a Bug	Impact on me:	None
Category:	MySQL Server: InnoDB storage engine	Severity:	S5 (Performance)
Version:	5.5.7	OS:	Any
Assigned to:	Sunny Bains	CPU Architecture:	Any

Description:
Taking one buffer pool and a set total amount of memory as a base, there is only a small performance improvement if the number of buffer pools <8.

At 8 buffer pools, performance is about the same.

And, a serious performance degradation shows if number of buffer pools >8.

How to repeat:
https://steam.mysql.com/Bench:MultipleBufferPoolInstances (TPC-C and Sysbench test results)

Why was this marked as "not a bug"?

The bug was closed by Sunny in the InnoDB team.

[23 Jan 2012 9:44] Michael Izioumtchenko:

I'm not sure if it's really a bug. I don't think we can expect performance improvements for any workload, with the dependency being 'the more buffer pools the better'. If we so expected, we would have set the default to 64. Performance depends on the workload. One case where multiple buffer pools are significantly better than single buffer pool is sysbench with secondary index search (as in Google's sysbench) and no adaptive hash index.

[12 May 2013 14:40] Sunny Bains:

I agree with Michael's comment.

If this is not a bug, please make it public.