Re: [PATCH v3] KVM: halt-polling: poll if emulated lapic timer will fire soon

From: Wanpeng Li
Date: Tue May 24 2016 - 03:14:59 EST

2016-05-24 14:59 GMT+08:00 Christian Borntraeger <borntraeger@xxxxxxxxxx>:
> On 05/24/2016 04:25 AM, Wanpeng Li wrote:
>> 2016-05-24 10:19 GMT+08:00 Wanpeng Li <kernellwp@xxxxxxxxx>:
>>> 2016-05-24 2:01 GMT+08:00 David Matlack <dmatlack@xxxxxxxxxx>:
>>>> On Sun, May 22, 2016 at 5:42 PM, Wanpeng Li <kernellwp@xxxxxxxxx> wrote:
>>>>> From: Wanpeng Li <>
>>>> I'm ok with this patch, but I'd like to better understand the target
>>>> workloads. What type of workloads do you expect to benefit from this?
>>> dynticks guests I think is one of workloads which can get benefit,
>>> there are lots of upcoming fire timers captured by my feature. Even
>>> during TCP testing. And also the workload of Yang's.
>> Do you think I should add an module parameter to enable/disable it
>> during module insmod or current patch is fine?
> What about getting rid of this hunk
> - val = 10000;
> + val = halt_poll_ns_base;
> and then rename "halt_poll_ns_base" into "halt_poll_ns_timer" that
> can be changed as module parameter?

Good idea, actually I remember Paolo mentioned to change this as an
module parameter in another thread.

> I also experimented with an s390 implementation, which seems pretty straightforward.
> It is probably something like the following (whitespace damaged due to pcopy/paste)
> and needs more testing.

Great work, Christian. I will send out a new version w/ module parameter.

Wanpeng Li