lkml.org 
[lkml]   [2008]   [May]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 1/2] bitreversal program
On Tue, May 20, 2008 at 05:57:37PM +0200, Soumyadip Das Mahapatra wrote:
> On Tue, 20 May 2008, Benoit Boissinot wrote:
>> On Tue, May 20, 2008 at 5:25 PM, Soumyadip Das Mahapatra
>> <kernelhacker@visualserver.org> wrote:
>>> I know that my bitrev8() takes more instructions than that
>>> of yours. But we have to think about faster access of cpu cache over that
>>> of memory cache(which your bit_rev_table uses).
>>
>> I didn't review your patch, sorry.
>> But I'm pretty sure that your patch won't be considered unless you
>> provide benchmarks
>> with numbers for different CPU/architecture.
>> Ideally you should provide a script to test the correctness and the
>> performance of your
>> change that anyone could run on his computer.
>
> Thanks Benoit for giving me such a precious advice. But sorry, I dont
> have any benchmarking system in my hand(how can i have? i am just a
> student, not a professional).
> So if you do me a favour and kindly do it for me, please :-)

A quick benchmarking (that you should have done at least one your
computer gives for 100000000 iterations):
old:
real 0m1.631s
user 0m1.628s
sys 0m0.004s

new:
real 0m5.553s
user 0m5.540s
sys 0m0.004s

So I guess there's no need to discuss this further.

regards,

Benoit

--
:wq


\
 
 \ /
  Last update: 2008-05-20 18:41    [W:0.297 / U:0.012 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site