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Re: [Xen-devel] [PATCH RFC V11 15/18] kvm : Paravirtual ticketlocks support for linux guests running on KVM hypervisor

On 08/02/2013 02:53 PM, Ingo Molnar wrote:

* Raghavendra K T <raghavendra.kt@xxxxxxxxxxxxxxxxxx> wrote:

On 08/01/2013 02:34 PM, Raghavendra K T wrote:
On 08/01/2013 01:15 PM, Gleb Natapov wrote:
Shall I consider this as an ack for kvm part?

For everything except 18/18. For that I still want to see numbers. But
18/18 is pretty independent from the reset of the series so it should
not stop the reset from going in.

Yes. agreed.
I am going to evaluate patch 18 separately and come with results for
that. Now we can consider only 1-17 patches.


32 core machine with HT off 32 vcpu guests.
base = 3.11-rc + patch 1 -17 pvspinlock_v11
patched = base + patch 18

                   dbench  (Throughput in MB/sec higher is better)
       base      stdev       patched    stdev       %improvement
1x 14584.3800   146.9074   14705.1000   163.1060     0.82773
2x  1713.7300    32.8750    1717.3200    45.5979     0.20948
3x   967.8212    42.0257     971.8855    18.8532     0.41994
4x   685.2764    25.7150     694.5881     8.3907     1.35882

Please list stddev in percentage as well ...

Sure. will do this from next time.

a blind stab gave me these figures:

       base      stdev       patched    stdev       %improvement
3x   967.8212    4.3%     971.8855      1.8%     0.4

That makes the improvement an order of magnitude smaller than the noise of
the measurement ... i.e. totally inconclusive.

Okay. agreed.

I always had seen the positive effect of the patch since it uses ple
handler heuristics, and thus avoiding the directed yield to vcpu's in
halt handler. But the current results clearly does not conclude
anything favoring that. :(

So please drop patch 18 for now.

Also please cut the excessive decimal points: with 2-4% noise what point
is there in 5 decimal point results??


Ingo, do you think now the patch series (patch 1 to 17) are in good
shape? or please let me know if you have any concerns to be

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