On Thu, Jul 11, 2013 at 02:43:03PM +0530, Raghavendra K T wrote: > On 07/10/2013 04:03 PM, Gleb Natapov wrote: > [...] trimmed > > >>>Yes. you are right. dynamic ple window was an attempt to solve it. > >>> > >>>Probelm is, reducing the SPIN_THRESHOLD is resulting in excess halt > >>>exits in under-commits and increasing ple_window may be sometimes > >>>counter productive as it affects other busy-wait constructs such as > >>>flush_tlb AFAIK. > >>>So if we could have had a dynamically changing SPIN_THRESHOLD too, that > >>>would be nice. > >>> > >> > >>Gleb, Andrew, > >>I tested with the global ple window change (similar to what I posted > >>here https://lkml.org/lkml/2012/11/11/14 ), > >This does not look global. It changes PLE per vcpu. > > Okay. Got it. I was thinking it would change the global value. But IIRC > It is changing global sysfs value and per vcpu ple_window. > Sorry. I missed this part yesterday. > Yes, it changes sysfs value but this does not affect already created vcpus. > > > >>But did not see good result. May be it is good to go with per VM > >>ple_window. > >> > >>Gleb, > >>Can you elaborate little more on what you have in mind regarding per > >>VM ple_window. (maintaining part of it as a per vm variable is clear > >>to > >> me), but is it that we have to load that every time of guest entry? > >> > >Only when it changes, shouldn't be to often no? > > Ok. Thinking how to do. read the register and writeback if there need > to be a change during guest entry? > Why not do it like in the patch you've linked? When value changes write it to VMCS of the current vcpu. -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
