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Re: [Xen-devel] [PATCH for 4.5 v4 1/4] xen: add real time scheduler rtds

On mer, 2014-09-24 at 14:35 +0100, George Dunlap wrote:
> On 09/24/2014 02:32 PM, Jan Beulich wrote:
> >>>> On 24.09.14 at 15:14, <dario.faggioli@xxxxxxxxxx> wrote:
> >> On mer, 2014-09-24 at 13:09 +0100, Jan Beulich wrote:
> >>> Furthermore the function appears to lack serialization with other
> >>> scheduler operations.
> >>>
> >> Not sure what you mean here. There's only one lock serializing
> >> everything in this scheduler, and it's already taken when this is
> >> called, the only exception being when it's called from rt_alloc_vdata().
> >>
> >> Is it that one you're referring to?
> > No. The call path do_domctl() -> sched_adjust() -> rt_dom_cntl()
> > doesn't take any scheduler related locks afaics.
> Indeed.

So, Meng, I think all we said in this thread makes sense:
 - sanity checking input params in rt_dom_cntl()
 - serialize rt_dom_cntl() itself against the global lock
 - move the call to rt_update_deadline() from _alloc to _insert

Probably in this priority order. :-)


<<This happens because I choose it to happen!>> (Raistlin Majere)
Dario Faggioli, Ph.D, http://about.me/dario.faggioli
Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)

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