Re: [PATCH RFC V8 0/17] Paravirtualized ticket spinlocks

From: Raghavendra K T
Date: Mon May 07 2012 - 09:39:20 EST


On 05/07/2012 06:52 PM, Avi Kivity wrote:
On 05/07/2012 04:20 PM, Raghavendra K T wrote:
On 05/07/2012 05:36 PM, Avi Kivity wrote:
On 05/07/2012 01:58 PM, Raghavendra K T wrote:
On 05/07/2012 02:02 PM, Avi Kivity wrote:
On 05/07/2012 11:29 AM, Ingo Molnar wrote:
This is looking pretty good and complete now - any objections
from anyone to trying this out in a separate x86 topic tree?

No objections, instead an

Acked-by: Avi Kivity<avi@xxxxxxxxxx>

[...]

(Less is better. Below is time elapsed in sec for x86_64_defconfig
(3+3 runs)).

BASE BASE+patch %improvement
mean (sd) mean (sd)
case 1x: 66.0566 (74.0304) 61.3233 (68.8299) 7.16552
case 2x: 1253.2 (1795.74) 131.606 (137.358) 89.4984
case 3x: 3431.04 (5297.26) 134.964 (149.861) 96.0664


You're calculating the improvement incorrectly. In the last case, it's
not 96%, rather it's 2400% (25x). Similarly the second case is about
900% faster.


You are right,
my %improvement was intended to be like
if
1) base takes 100 sec ==> patch takes 93 sec
2) base takes 100 sec ==> patch takes 11 sec
3) base takes 100 sec ==> patch takes 4 sec

The above is more confusing (and incorrect!).

Better is what you told which boils to 10x and 25x improvement in case
2 and case 3. And IMO, this *really* gives the feeling of magnitude of
improvement with patches.

I ll change script to report that way :).


btw, this is on non-PLE hardware, right? What are the numbers for PLE?

Sure.
I 'll get hold of a PLE mc and come up with the numbers soon. but I
'll expect the improvement around 1-3% as it was in last version.

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