Re: [PATCH] Do not include throttled time as steal time

From: Mike wolf
Date: Mon Dec 05 2011 - 12:10:29 EST


On 12/05/2011 10:20 AM, Peter Zijlstra wrote:
On Mon, 2011-12-05 at 09:08 -0600, Mike wolf wrote:

Hi Mike, couple of problems with this:

1) You failed to CC the appropriate maintainers for the piece of code
you're trying to have changed. When in doubt see the MAINTAINERS
file ;-)
yes will do
2) You failed to CC the people who wrote the feature you're having a
problem with.
ok, I will add Glauber and others when the patch is respun/resubmitted
When the linux kernel is running as the guest OS and is configured
for bandwidth control and steal time reporting, it can be confusing
to users to see the throttled time show up in the steal time stats.
The user will think they are not getting the cpu resources they have
been configured.
Supposedly this is a BAD (tm) thing :-)

Signed-off-by: Mike Wolf<mjw@xxxxxxxxxxxxxxxxxx>
---
kernel/sched_fair.c | 4 ++--
kernel/sched_stats.h | 7 ++++++-
2 files changed, 8 insertions(+), 3 deletions(-)
3) You blink you loose, those files don't exist anymore. Patches are
best provided against the development tree of the particular subsystem
you're working against.

In this particular case tip/master is your target.

static inline void sched_info_depart(struct task_struct *t)
{
+ struct task_group *tg = task_group(t);
+ struct cfs_rq *cfs_rq;
unsigned long long delta = task_rq(t)->clock -
t->sched_info.last_arrival;

+ cfs_rq = tg->cfs_rq[smp_processor_id()];
rq_sched_info_depart(task_rq(t), delta);

- if (t->state == TASK_RUNNING)
+
+ if (t->state == TASK_RUNNING&& !throttled_hierarchy(cfs_rq))
sched_info_queued(t);
}
4) so there's a lot more steal time crap all over the scheduler, you
failed to explain why only this particular bit is important enough to
change.
I will make sure to explain why you would want the patch functionality better
when I resubmit.



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