On Thu, 2015-10-08 at 18:23 +0100, Andrew Cooper wrote: > On 08/10/15 17:46, George Dunlap wrote: > > On 08/10/15 16:20, Andrew Cooper wrote:
> > > There are a lot of codepaths, but I cant see one which is > > > definitely > > > called with interrupts disables. (OTOH, I can see several where > > > interrupts are definitely enabled). > > Oh, I think I misunderstood you. You meant, "No codepaths *calling > > into* generic scheduling code should need interrupts disabled at > > all". > > I can certainly believe that to be true in most cases; there's no > > sense > > in saving the flags if we don't need to. > > My original statement came from the observation that schedule() runs > with interrupts disabled, and takes between 2.2 and 4 microseconds to > run (as measured during the ticketlock performance analysis). > Ok, this part, I got, I think. BTW, do you still have the scripts/harness/whatever to perform such analysis? I'm asking because I'm about to give it a try at reducing the amount of time during which the scheduler keeps interrupt disabled. If I manage, it'd be nice to retry it, an get updated numbers. > I am going to go out on a limb and say that the majority of that time > does not need to be spent with interrupts disabled. I might easily > be > wrong, but I suspect I am not. > I'll have a look and let you know what I find. Regards, Dario -- <<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)
signature.asc
Description: This is a digitally signed message part
_______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
