Re: [Xen-devel] [PATCH] xen/sched: fix locking in sched_tick_[suspend|resume]()

[Jürgen Groß <jgross@xxxxxxxx>]

On 04.10.19 16:08, George Dunlap wrote:
> On 10/4/19 7:40 AM, Juergen Gross wrote:
> > sched_tick_suspend() and sched_tick_resume() should not call the
> > scheduler specific timer handlers in case the cpu they are running on
> > is just being moved to or from a cpupool.
> >
> > Use a new percpu lock for that purpose.
> Is there a reason we can't use the pcpu_schedule_lock() instead of
> introducing a new one?  Sorry if this is obvious, but it's been a while
> since I poked around this code.
Lock contention would be higher especially with credit2 which is using a
per-core or even per-socket lock. We don't care about other scheduling
activity here, all we need is a guard against our per-cpu scheduler
data being changed beneath our feet.


Juergen

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