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Re: [PATCH] Optimize MIPS memcpy
On 30/10/2012, at 7:00 AM, Steve Ellcey wrote:
> On Wed, 2012-10-17 at 10:29 -0700, Steve Ellcey wrote:
>
>> OK, Here is a version of memcpy that uses the STORE_STREAMING prefetch.
>> While it is optimized for a 32 byte prefetch, it will work correctly
>> regardless of the size of the prefetch.
>>
>> Is this version OK to checkin?
>>
>> Steve Ellcey
>> sellcey@mips.com
>
> Maxim, have you had a chance to test this version of memcpy for MIPS?
I have tested your latest version. Good news: there are no correctness issues. Bad news: it underperforms compared to my patch by 2-3 times on both N32 and N64 (didn't test O32) on the benchmark that I used. I've run the benchmark several times and results are consistent. I use oprofile on libc.so to determine how much time is spent in memcpy.
Would you please confirm that your current implementation is faster on YOUR benchmark than my patch in http://sourceware.org/ml/libc-ports/2012-09/msg00000.html ? Please make sure that PREFETCH macro in ports/sysdeps/mips/sys/asm.h gets defined to "pref", not "nop", in your build.
Thanks,
--
Maxim Kuvyrkov
CodeSourcery / Mentor Graphics