Re: [PATCH RFC] [X86] performance improvement for memcpy_64.S byavoid memory miss predication.

[Ingo Molnar]

* Ling Ma <linguranus@xxxxxxxxx> wrote:

> Hi Ingo
> Thanks for your suggestion. I used 'perf stat --repeat 10
> /develop/trunk/memcpy/static'  to measure before/after patch.
> 
> The test program I wrote:
>  for (i = 64; i < 4096 *4; i ++)
>       do_memcpy(src, dst, i);
> 
> when src offset is 0xbe000, dst is 0xad008, the measured result:
> 
> Before patch:
>  Performance counter stats for '/develop/trunk/memcpy/static' (10 runs):
>   <not counted>  task-clock-msecs
>   <not counted>  context-switches
>   <not counted>  CPU-migrations
>   <not counted>  page-faults
>   <not counted>  cycles
>   <not counted>  instructions
>   <not counted>  cache-references
>   <not counted>  cache-misses
>    37.408743997  seconds time elapsed   ( +-   0.222% )

hm, on what kind of CPU have you run this? Why are those events not 
counting? Is it some older, Pentium-4 alike CPU perhaps?

	Ingo
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/