On Fri, Nov 23, 2012 at 9:31 PM, Ingo Molnar <mi...@kernel.org> wrote:
>
> * Ingo Molnar <mi...@kernel.org> wrote:
>
>> * Alex Shi <lkml.a...@gmail.com> wrote:
>>
>> > >
>> > > Those of you who would like to test all the latest patches are
>> > > welcome to pick up latest bits at tip:master:
>> > >
>> > > git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git master
>> > >
>> >
>> > I am wondering if it is a problem, but it still exists on HEAD:
>> > c418de93e39891
>> > http://article.gmane.org/gmane.linux.kernel.mm/90131/match=compiled+with+name+pl+and+start+it+on+my
>> >
>> > like when just start 4 pl tasks, often 3 were running on node
>> > 0, and 1 was running on node 1. The old balance will average
>> > assign tasks to different node, different core.
>>
>> This is "normal" in the sense that the current mainline
>> scheduler is (supposed to be) doing something similar: if the
>> node is still within capacity, then there's no reason to move
>> those threads.
>>
>> OTOH, I think with NUMA balancing we indeed want to spread
>> them better, if those tasks do not share memory with each
>> other but use their own memory. If they share memory then they
>> should remain on the same node if possible.
I rewrite the little test case by assemble:
==
.text
.global _start
_start:
do_nop:
nop
nop
jmp do_nop
==
It reproduced the problem on latest tip/master, HEAD: 7cb989d0159a6f43104992f18
like for 4 above tasks running, 3 of them running on node 0, one
running on node 1.
If kernel can detect the LLC of CPU is allowed for tasks aggregate, it's a nice
feature. if not, the aggregate may cause more cache missing.
>
> Could you please check tip:master with -v17:
>
> git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git master
>
> ?
>
> It should place your workload better than v16 did.
>
> Note, you might be able to find other combinations of tasks that
> are not scheduled NUMA-perfectly yet, as task group placement is
> not exhaustive yet.
>
> You might want to check which combination looks the weirdest to
> you and report it, so I can fix any remaining placement
> inefficiencies in order of importance.
>
> Thanks,
>
> Ingo
--
Thanks
Alex
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