Re: Spinlock performance improvement proposal - Mailing list pgsql-hackers

From Bruce Momjian
Subject Re: Spinlock performance improvement proposal
Date
Msg-id 200109291932.f8TJWow01846@candle.pha.pa.us
Whole thread Raw
In response to Re: Spinlock performance improvement proposal  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
OK, testing now with 1000 backends and 2000 buffers.  Will report.

> Bruce Momjian <pgman@candle.pha.pa.us> writes:
> > No scale factor, as I illustrated from the initialization command I
> > used.  Standard buffers too.  Let me know what values I should use for
> > testing.
> 
> Scale factor has to be >= max number of clients you use, else you're
> just measuring serialization on the "branch" rows.
> 
> I think the default NBuffers (64) is too low to give meaningful
> performance numbers, too.  I've been thinking that maybe we should
> raise it to 1000 or so by default.  This would trigger startup failures
> on platforms with small SHMMAX, but we could tell people to use -B until
> they get around to fixing their kernel settings.  It's been a long time
> since we fit into a 1-MB shared memory segment at the default settings
> anyway, so maybe it's time to select somewhat-realistic defaults.
> What we have now is neither very useful nor the lowest common
> denominator...
> 
>             regards, tom lane
> 

--  Bruce Momjian                        |  http://candle.pha.pa.us pgman@candle.pha.pa.us               |  (610)
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