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
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