Re: [Qemu-devel] [PATCH v4 1/5] cpu: Provide vcpu throttling interface

["Jason J. Herne" <jjherne@linux.vnet.ibm.com>]

On 08/01/2015 05:40 AM, Paolo Bonzini wrote:
>
>
> On 31/07/2015 20:11, Jason J. Herne wrote:
>>>>
>>>
>>> Doh! Yep :). This problem is an artifact of moving the timer_mod from
>>> cpu_throttle_thread into cpu_throttle_timer_tick. I'll have to go back
>>> to the review comments and look at why that was done.
>>
>> So, we made that change in v3 to eliminate the per cpu timer. With a per
>> cpu timer we avoid this problem and we no longer need to worry about
>> a throttle_thread_scheduled, and timers stacking. Paolo, you had originally
>> argued in favor of this change. With what we know now, do you still think
>> having only a single timer is best? Or should I switch back to a timer per
>> cpu? With a timer per cpu we can simply reset the timer immediately after
>> the sleep.
>
> It's okay to have a single timer, only the formulas have to be
> corrected: either you remove the pct/(1-pct) from the callback or you
> add a /(1-pct) to the timer_mod.
>
> Paolo

Paolo,

You are correct here. I've adjusted the timer formula and tested. 
Everything seems to be playing nicely now. Sorry it took me a month to 
get to this. I got pulled into some critical work and improved 
auto-converge took a back seat. I know it is a pain to go back to 
something you have not seen in a month so I appreciate any attention 
this gets :). A new patch set will be inbound shortly...

-- 
-- Jason J. Herne (jjherne@linux.vnet.ibm.com)