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Re: [PATCH] Expand mempcpy into memcpy
From: David Miller <davem@davemloft.net>
Date: Wed, 06 Feb 2013 13:40:00 -0500 (EST)
> From: Ondřej Bílka <neleai@seznam.cz>
> Date: Wed, 6 Feb 2013 18:40:21 +0100
>
>> This makes all mempcpy call to call memcpy instead.
>>
>> There are two reasons, one is that it will simplify maintainance.
>> Second is that posible performance gains are saving one addition and
>> perhaps spilling one register. Problem is that implementation is quite
>> big - 1105 bytes on x64. Probably cost of instruction/branch cache
>> misses outweigth speedup we gained.
>>
>> I will move unused inline functions later.
>
> The overhead of mempcpy vs. memcpy on sparc is exactly 2 instructions
> and 1 extra cycle.
Correction, the extra overhead of mempcpy on sparc is actually zero.