Message-ID: <51DE8EC6.6020700@linux.vnet.ibm.com>
Date: Thu, 11 Jul 2013 16:23:58 +0530
From: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Organization: IBM
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To: Gleb Natapov <gleb@redhat.com>
CC: Andrew Jones <drjones@redhat.com>, mingo@redhat.com, ouyang@cs.pitt.edu,
        habanero@linux.vnet.ibm.com, jeremy@goop.org, x86@kernel.org,
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        attilio.rao@citrix.com, gregkh@suse.de, agraf@suse.de,
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        srivatsa.vaddagiri@gmail.com
Subject: Re: [PATCH RFC V9 0/19] Paravirtualized ticket spinlocks
References: <20130626113744.GA6300@hawk.usersys.redhat.com> <20130626125240.GY18508@redhat.com> <51CAEF45.3010203@linux.vnet.ibm.com> <20130626161130.GB18152@redhat.com> <51CB2AD9.5060508@linux.vnet.ibm.com> <51DBD3C2.2040807@linux.vnet.ibm.com> <20130710103325.GP24941@redhat.com> <51DE771F.7070805@linux.vnet.ibm.com> <20130711094833.GC8575@redhat.com> <51DE849E.4020405@linux.vnet.ibm.com> <20130711101104.GF8575@redhat.com>
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On 07/11/2013 03:41 PM, Gleb Natapov wrote:
> On Thu, Jul 11, 2013 at 03:40:38PM +0530, Raghavendra K T wrote:
>>>>>> 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.
>>>
>>
>> Yes. can be done. So the running vcpu's ple_window gets updated only
>> after next pl-exit. right?
> I am not sure what you mean. You cannot change vcpu's ple_window while
> vcpu is in a guest mode.
>

I agree with that. Both of us are on the same page.
  What I meant is,
suppose the per VM ple_window changes when a vcpu x of that VM  was running,
it will get its ple_window updated during next run.

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