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

[Raghavendra K T]

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 :).

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