Re: [Qemu-devel] sh : performance problem

[Lionel Landwerlin]

Le mercredi 04 mars 2009 à 00:46 +0900, Shin-ichiro KAWASAKI a écrit :
> Lionel Landwerlin wrote:
> > Shin-ichiro,
> > 
> > Sorry, but I cannot apply your patch cleanly on the last qemu-svn.
> > 
> > Instead, I would like to try another approach. The patch you proposed to
> > find (or not) a valid TLB entry has a complexity of O(log2(n)) (or
> > something like that if I remember) instead here is a patch with a
> > complexity of O(1).
> 
> Good work.  I evaluated your patch on my environment, measuring
> compile time for empty main() with gcc.
> 
>   sh4 : 5.8 [seconds]     O(n) utlb search.
>   sh4 : 4.6 [seconds]     O(log2(n)) utlb search.
>   sh4 : 4.1 [seconds]     O(1) utlb search by Lionel
>   arm : 0.8 [seconds]     (-M versatilepb + Debian ARM)
> 
> Your patch has a nice score!
> 
> Now I've done the work to increase number of utlb entries from 64 to 256,
> and found that the score get arround 2.4 seconds.
> I'm trying to increase it to 4096.  Your O(1) search will be more important
> as the entry number increase.

We should setup a git repository to improve that or at least work on the
same basis.

Do you have a lot of patch on top of the last svn ?


-- 
Lionel Landwerlin <address@hidden>