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
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 some user
run several processes pinned to each CPU, one for each CPU
(as many
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