On Sunday 13 October 2002 6:17 am, Erich Focht wrote:
> Hi,
>
<snip>
>
> Schedulers tested (all on top of discontigmem for ia64):
>
> A: vanilla O(1) scheduler from 2.5.39
> B: Michael Hohnbaums simple NUMA scheduler (latest published rev 2)
> C: pooling NUMA scheduler with initial load balancing (patches 01+02
> from the 5 patches sent out)
> D: node affine NUMA scheduler (patches 01+02+03)
> E: node affine NUMA scheduler with dynamic homenode (patches 01+02+03+05)
>
> All results are averages over several measurements, the numbers in braces
> are the standard deviation or "error bars".
>
> There's a lot to say about the results, e.g that E is the best because it
> has most features. But the only comment I really want to make on this now
> is: the numa_test is not good enough for testing node affinity as
> "hackbench 20" doesn't seem to disturb the initially balance too much.
> I'll improve this to make it more realistic. Otherwise it's good enough
> to see the advantage of not moving around tasks across the nodes.
Thanks very much for doing this Erich. I have run the SPEC SDET benchmark on
2.5.41-mm3, with your "E" scheduler, and Michael's rev 1 & 2 scheduler. At
this time I don't think I can publish actual throughput results, but only %
differences, to abide by SPEC rules. These results are not considered
compliant by SPEC, and are used only to compare performance difference of
these scheduler implementations.
SDET simulates the multiuser development environment, and may be useful for
environments like universities, etc. More information can be found at:
http://www.spec.org/osg/sdm91/
SDET was configured to simulate 1, 2, 4, 8, 16, 32, 64 and 128 users. SDET
appears to benefit from spreading out exec'd processes on initial placement,
but there also exists scenarios where exec'd tasks should reside on the same
node. Ideally, each of the scripts run in parallel would benefit from being
initially spread out across the nodes, but the processes exec'd _within_ each
script would benefit from being placed within the node. I don't expect any
scheduler to to identify and optimize for that today, but maybe that's
something to work on in the future, who knows?
Anyway, on to the results. Almost forgot, this is on a 16 way NUMA-Q box.
These results are not actual results, but normalized to a baseline for
2.5.41-mm3 for 1 user:
1 user
vanilla 100
erich-E 062
michael-r1 103
michael-r2 065
2 users
vanilla 191
erich-E 112
michael-r1 180
michael-r2 116
4 users
vanilla 288
erich-E 213
michael-r1 306
michael-r2 208
8 users
vanilla 426
erich-E 336
michael-r1 405
michael-r2 333
16 users
vanilla 462
erich-E 412
michael-r1 464
michael-r2 427
32 users
vanilla 438
erich-E 425
michael-r1 436
michael-r2 332
64 users
vanilla 420
erich-E 410
michael-r1 430
michael-r2 432
128 users
vanilla 413
erich-E 397
michael-r1 413
michael-r2 398
In Michael's rev 1, initial placement of an exec'd task would be on the same
CPU if nr_running <=2, (sched_best_cpu) which I believe why the low loaded
tests perform better. This is where I believe the tasks within a script are
getting scheduled on the same CPU/node and benefit from locality. Erich's
and Michael's rev2 place the newly exec'd task on the least loaded cpu, which
tends to spread those tasks exec'd within a script across nodes and hurt
thoughput in those cases. In the higher load cases, most of the results
appear similar.
Anyway, I used SDET to give yet another view of how these schedulers can
affect performance. At this point I personally do not have a preference on
which scheduler one to use. I'd like to hear from people who have made BIG
changes to the scheduler (hint, hint) what they think of these
implementations, and where we should go from here. We should probably decide
which implementation to use, and what we need to do to make it ready for
inclusion, right?
Andrew Theurer
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This archive was generated by hypermail 2b29 : Tue Oct 15 2002 - 22:00:50 EST