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.
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?
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