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SubjectRe: [PATCH RFC] x86:Improve memset with general 64bit instruction
From
Any further comments  ?

Thanks
Ling


2014-04-08 22:00 GMT+08:00, Ling Ma <ling.ma.program@gmail.com>:
> Andi,
>
> The below is compared result on older machine(cpu info is attached):
> That shows new code get better performance up to 1.6x.
>
> Bytes: ORG_TIME: NEW_TIME: ORG vs NEW:
> 7 0.87 0.76 1.14
> 16 0.99 0.68 1.45
> 18 1.07 0.77 1.38
> 21 1.09 0.78 1.39
> 25 1.11 0.77 1.44
> 30 1.12 0.73 1.53
> 36 1.15 0.75 1.53
> 38 1.12 0.75 1.49
> 62 1.18 0.77 1.53
> 75 1.25 0.79 1.58
> 85 1.28 0.80 1.60
> 120 1.33 0.82 1.62
> 193 1.45 0.88 1.64
> 245 1.48 0.96 1.54
> 256 1.45 0.90 1.61
> 356 1.61 1.02 1.57
> 601 1.78 1.22 1.45
> 958 2.04 1.47 1.38
> 1024 2.07 1.48 1.39
> 2048 2.80 2.21 1.26
>
> Thanks
> Ling
>
> 2014-04-08 0:42 GMT+08:00, Andi Kleen <andi@firstfloor.org>:
>> ling.ma.program@gmail.com writes:
>>
>>> From: Ling Ma <ling.ml@alibaba-inc.com>
>>>
>>> In this patch we manage to reduce miss branch prediction by
>>> avoiding using branch instructions and force destination to be aligned
>>> with general 64bit instruction.
>>> Below compared results shows we improve performance up to 1.8x
>>> (We modified test suit from Ondra, send after this patch)
>>
>> You didn't specify the CPU?
>>
>> I assume it's some Atom, as nothing else uses these open coded functions
>> anymore?
>>
>> -Andi
>>
>> --
>> ak@linux.intel.com -- Speaking for myself only
>>
>


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