linux-kernel - Re: [PATCH] kvm: add halt_poll

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Message-ID: <54D887F4.8000903@linux.intel.com>
Date:	Mon, 09 Feb 2015 18:12:04 +0800
From:	Xiao Guangrong <guangrong.xiao@...ux.intel.com>
To:	Paolo Bonzini <pbonzini@...hat.com>, linux-kernel@...r.kernel.org,
	kvm@...r.kernel.org
CC:	riel@...hat.com, mtosatti@...hat.com, rkrcmar@...hat.com,
	jan.kiszka@...mens.com, dmatlack@...gle.com
Subject: Re: [PATCH] kvm: add halt_poll_ns module parameter



On 02/09/2015 05:06 PM, Paolo Bonzini wrote:
>
>
> On 09/02/2015 09:22, Xiao Guangrong wrote:
>>
>>
>> On 02/06/2015 08:48 PM, Paolo Bonzini wrote:
>>
>>>
>>> +unsigned int halt_poll_ns = 0;
>>> +module_param(halt_poll_ns, uint, S_IRUGO | S_IWUSR);
>>> +
>>
>> Can we make this parameter be changeable? So that we can tune it
>> on the fly.
>
> It is changeable (S_IWUSR).

Oh... Yes, sorry for my careless.

>
>>>        finish_wait(&vcpu->wq, &wait);
>>> +    cur = ktime_get();
>>
>> We can move this into the tracepoint to avoid the workload if the
>> tracepoint is not enabled.
>
> You have a point.  I didn't do it because I expect that halt_poll_ns
> will be always enabled as soon as it auto-tunes, and in that case you'll
> always have to do the ktime_get() for autotuning purposes.

Great, look forward to your future patches. ;)

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