lkml.org 
[lkml]   [2012]   [Oct]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH RFC 1/2] kvm: Handle undercommitted guest case in PLE handler
On 10/18/2012 06:09 PM, Avi Kivity wrote:
> On 10/09/2012 08:51 PM, Raghavendra K T wrote:
>> Here is the summary:
>> We do get good benefit by increasing ple window. Though we don't
>> see good benefit for kernbench and sysbench, for ebizzy, we get huge
>> improvement for 1x scenario. (almost 2/3rd of ple disabled case).
>>
>> Let me know if you think we can increase the default ple_window
>> itself to 16k.
>>
>
> I think so, there is no point running with untuned defaults.
>

Oaky.

>>
>> I can respin the whole series including this default ple_window change.
>
> It can come as a separate patch.

Yes. Will spin it separately.

>
>>
>> I also have the perf kvm top result for both ebizzy and kernbench.
>> I think they are in expected lines now.
>>
>> Improvements
>> ================
>>
>> 16 core PLE machine with 16 vcpu guest
>>
>> base = 3.6.0-rc5 + ple handler optimization patches
>> base_pleopt_16k = base + ple_window = 16k
>> base_pleopt_32k = base + ple_window = 32k
>> base_pleopt_nople = base + ple_gap = 0
>> kernbench, hackbench, sysbench (time in sec lower is better)
>> ebizzy (rec/sec higher is better)
>>
>> % improvements w.r.t base (ple_window = 4k)
>> ---------------+---------------+-----------------+-------------------+
>> |base_pleopt_16k| base_pleopt_32k | base_pleopt_nople |
>> ---------------+---------------+-----------------+-------------------+
>> kernbench_1x | 0.42371 | 1.15164 | 0.09320 |
>> kernbench_2x | -1.40981 | -17.48282 | -570.77053 |
>> ---------------+---------------+-----------------+-------------------+
>> sysbench_1x | -0.92367 | 0.24241 | -0.27027 |
>> sysbench_2x | -2.22706 |-0.30896 | -1.27573 |
>> sysbench_3x | -0.75509 | 0.09444 | -2.97756 |
>> ---------------+---------------+-----------------+-------------------+
>> ebizzy_1x | 54.99976 | 67.29460 | 74.14076 |
>> ebizzy_2x | -8.83386 |-27.38403 | -96.22066 |
>> ---------------+---------------+-----------------+-------------------+
>
> So it seems we want dynamic PLE windows. As soon as we enter overcommit
> we need to decrease the window.
>

Okay.
I have some rough idea on the implementation. I 'll try that after this
V2 experiments are over.
So in brief, I have this in my queue priority wise

1) V2 version of this patch series( in progress)
2) default PLE window
3) preemption notifiers
4) Pv spinlock



\
 
 \ /
  Last update: 2012-10-19 11:01    [W:0.876 / U:0.036 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site