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

[Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>]

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:
>> (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.
>

speedup calculation is clear.

I think confusion for me was more because of the types of benchmarks.

I always did

|(patch - base)| * 100 / base


So,  for
(1) lesser is better sort of benchmarks,
improvement calculation would be like

|(patched -  base)| * 100/ patched
e.g for kernbench,

suppose base    = 150 sec
         patched = 100 sec
improvement = 50 % ( = 33% degradation of base)


(2) for higher is better sort of benchmarks improvement calculation 
would be like

|(patched - base)| * 100 / base

for e.g say for pgbench/ ebizzy...

     base = 100 tps (transactions per sec)
     patched = 150 tps

  improvement  = 50 % of pathched kernel ( OR 33 % degradation of base )


Is this is what generally done? just wanted to be on same page before 
publishing benchmark results, other than kernbench.