I wrote:
The Linux CFS scheduler prefers pinned tasks and unfairly
gives more CPU time to tasks that have set CPU affinity.
...
I believe I have now solved the problem, simply by setting:
for n in /proc/sys/kernel/sched_domain/cpu*/domain0/min_interval; do echo 0
> $n; done
for n
I wrote:
The Linux CFS scheduler prefers pinned tasks and unfairly
gives more CPU time to tasks that have set CPU affinity.
I believe I have now solved the problem, simply by setting:
for n in /proc/sys/kernel/sched_domain/cpu*/domain0/min_interval; do echo 0 >
$n; done
for n in /proc/s
On 10/10/15 11:59 AM, Wanpeng Li wrote:
Hi Paul,
On 10/8/15 4:19 PM, Mike Galbraith wrote:
On Tue, 2015-10-06 at 04:45 +0200, Mike Galbraith wrote:
On Tue, 2015-10-06 at 08:48 +1100, paul.sz...@sydney.edu.au wrote:
The Linux CFS scheduler prefers pinned tasks and unfairly
gives more CPU time t
Hi Paul,
On 10/8/15 4:19 PM, Mike Galbraith wrote:
On Tue, 2015-10-06 at 04:45 +0200, Mike Galbraith wrote:
On Tue, 2015-10-06 at 08:48 +1100, paul.sz...@sydney.edu.au wrote:
The Linux CFS scheduler prefers pinned tasks and unfairly
gives more CPU time to tasks that have set CPU affinity.
This
On Fri, 2015-10-09 at 08:55 +1100, paul.sz...@sydney.edu.au wrote:
> >> Good to see that you agree ...
> > Weeell, we've disagreed on pretty much everything ...
>
> Sorry I disagree: we do agree on the essence. :-)
P.S.
To some extent. If the essence is $subject, nope, we definitely
disagree.
On Fri, 2015-10-09 at 08:55 +1100, paul.sz...@sydney.edu.au wrote:
> Dear Mike,
>
> >>> I see a fairness issue ... but one opposite to your complaint.
> >> Why is that opposite? ...
> >
> > Well, not exactly opposite, only opposite in that the one pert task also
> > receives MORE than it's fair sh
Dear Mike,
>>> I see a fairness issue ... but one opposite to your complaint.
>> Why is that opposite? ...
>
> Well, not exactly opposite, only opposite in that the one pert task also
> receives MORE than it's fair share when unpinned. Two 100$ hogs sharing
> one CPU should each get 50% of that C
On Thu, 2015-10-08 at 21:54 +1100, paul.sz...@sydney.edu.au wrote:
> Dear Mike,
>
> > I see a fairness issue ... but one opposite to your complaint.
>
> Why is that opposite? I think it would be fair for the one pert process
> to get 100% CPU, the many oink processes can get everything else. That
On Thu, Oct 08, 2015 at 09:54:21PM +1100, paul.sz...@sydney.edu.au wrote:
> Good to see that you agree on the fairness issue... it MUST be fixed!
> CFS might be wrong or wasteful, but never unfair.
I've not yet had time to look at the case at hand, but there are wat is
called 'infeasible weight' s
Dear Mike,
> I see a fairness issue ... but one opposite to your complaint.
Why is that opposite? I think it would be fair for the one pert process
to get 100% CPU, the many oink processes can get everything else. That
one oink is lowly 10% (when others are 100%) is of no consequence.
What happe
On Tue, 2015-10-06 at 04:45 +0200, Mike Galbraith wrote:
> On Tue, 2015-10-06 at 08:48 +1100, paul.sz...@sydney.edu.au wrote:
> > The Linux CFS scheduler prefers pinned tasks and unfairly
> > gives more CPU time to tasks that have set CPU affinity.
> > This effect is observed with or without CGROUP
On Wed, 2015-10-07 at 07:44 +1100, paul.sz...@sydney.edu.au wrote:
> I agree that pinning may be bad... should not the kernel penalize the
> badly pinned processes?
I didn't say pinning is bad, I said was what you're seeing is not a bug.
-Mike
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Dear Mike,
>> ... the CFS is meant to be fair, using things like vruntime
>> to preempt, and throttling. Why are those pinned tasks not preempted or
>> throttled?
>
> Imagine you own a 8192 CPU box for a moment, all CPUs having one pinned
> task, plus one extra unpinned task, and ponder what would
On Tue, 2015-10-06 at 21:06 +1100, paul.sz...@sydney.edu.au wrote:
> And further... the CFS is meant to be fair, using things like vruntime
> to preempt, and throttling. Why are those pinned tasks not preempted or
> throttled?
Imagine you own a 8192 CPU box for a moment, all CPUs having one pinne
Dear Mike,
>> .. CFS ... unfairly gives more CPU time to [pinned] tasks ...
>
> If they can all migrate, load balancing can move any of them to try to
> fix the permanent imbalance, so they'll all bounce about sharing a CPU
> with some other hog, and it all kinda sorta works out.
>
> When most are
On Tue, 2015-10-06 at 08:48 +1100, paul.sz...@sydney.edu.au wrote:
> The Linux CFS scheduler prefers pinned tasks and unfairly
> gives more CPU time to tasks that have set CPU affinity.
> This effect is observed with or without CGROUP controls.
>
> To demonstrate: on an otherwise idle machine, as
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