Anyone interested in improving postgresql scaling?

[Kevin Way]

Kris Kennaway wrote:
> On Tue, Apr 17, 2007 at 02:51:55PM -0400, Kevin Way wrote:
>
>   
>> I built 7.0 as of 6 days ago, and ran the same test using 8-cores, ULE 
>> and 4BSD.  The results are available at:
>>
>> http://blog.insidesystems.net/articles/2007/04/11/postgresql-scaling-on-6-2-and-7-0
>>
>> Unfortunately, I can't run the additional tests, as the machines in 
>> question have now been deployed to production.  I should have similar 
>> equipment available in a few weeks, and will try the other tests at that 
>> point.
>>     
>
> That's better but still not comparable to my results.  One important
> change you may have missed was to enable MALLOC_PRODUCTION in
> /usr/src/lib/libc/stdlib/malloc.c.  This disables malloc debugging
> which may have significant overhead.
>
> My results from about a month ago:
>
>   http://people.freebsd.org/~kris/scaling/nickel.png
>
> The big dip between 5-7 clients is believed to be due to a ULE bug
> that has known cause but is not yet fixed (on dual core CPUs processes
> are bouncing around between the two cores too much).  The main point
> is that apart from this anomaly in the middle there is approximately
> linear scaling from 1 to 8 CPUs.  On your system it is not scaling
> linearly beyond 4.
>
> I do have some other changes in my kernel but I don't think any of
> them are enough to explain this difference.
>
> Anyway, get back to us when you can retest with the above change.
>
>   

Confirmed, I did miss MALLOC_PRODUCTION.  I incorrectly believed that I 
just needed an empty malloc.conf.  This is somewhat exciting news from 
my vantage point.  I'll post a corrected re-test as soon as I have 
another available 8-core machine.
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