Re: Opteron server and NUMA

[Alexander Charbonnet <alexander@charbonnet.com>]

I now think that lack of NUMA support isn't the problem.  I've done some 
benchmarking of my database-backed Perl Web app with the Apache benchmark 
tool, "ab".  I ran the same query with differing total requests and 
concurrency.  After the first time, which I did manually before the tests, 
all the results will be in the database query cache.  Therefore, I don't 
expect any disk I/O.

The results seem to be significantly slower than they should be.  Is this a 
problem with my config, the new x86-64 code, SMP stuff, or is it just the 
cost of doing business?

This table shows the time in seconds for each request x concurrency and 
kernel.  There's native with NUMA, native without NUMA, and finally Domain0 
(you may want to view this with a fixed font).

	NUMA	noNUMA	Dom0
20x1	44.8	45.5	67.4
20x2	23.2	24.0	36.6
20x3	17.9	18.4	30.2
20x4	13.3	13.5	23.9
20x8	14.6	14.6	23.6
40x2	46.1	47.5	72.8
40x4	25.2	26.6	46.1
40x8	28.7	27.8	40.4

Thanks,
Alex


On Friday 07 October 2005 03:58 am, Keir Fraser wrote:
> On 7 Oct 2005, at 00:09, Nicholas Lee wrote:
> >> Xen 3.0 on it.  I've found that I can compile SMP just fine, and it
> >> sees all
> >> four processors, but when I add K8 NUMA, the compile breaks.
> >
> > I just noted this complier breakage as well.
> >
> > Thinking about it, I expect the nature of Xen makes it tricky to get
> > going at the moment.
>
> We have some ideas about how to get this working, but you're right that
> it is not a totally trivial thing to fix. Don't hold your breath until
> at least 3.0 is out the door.
>
>   -- Keir
>
>
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