[U-Boot] [PATCH] arm: Use optimized memcpy and memset from linux

[Matthias Weißer]

Am 24.01.2011 17:13, schrieb Wolfgang Denk:
> Dear Matthias Weisser,
> 
> In message <1295884607-9044-1-git-send-email-weisserm at arcor.de> you wrote:
>> Using optimized versions of memset and memcpy from linux brings a quite
>> noticeable speed (x2 or better) improvement for these two functions.
>>
>> Size impact:
>>
>> C version:
>>    text    data     bss     dec     hex filename
>>  202862   18912  266456  488230   77326 u-boot
>>
>> ASM version:
>>    text    data     bss     dec     hex filename
>>  203798   18912  266288  488998   77626 u-boot
> 
> How exactly did you measure the speed improvement?

I inserted a printf before and after calls to these functions with sizes
of 1MB or more each. I then measured the times between these printfs
using grabserial (http://elinux.org/Grabserial). In both cases caches
where enabled.

To be precise: As memset test case I used the memset(.., 0, ..) of the
malloc pool (which was 4MB in my case) and a memcpy from flash to RAM
which I inserted in cmd_bootm.c of about 2.2MB (see RFC patch
http://patchwork.ozlabs.org/patch/79480/ for exact location of the memcpy).

Do you think a factor of 2 is not possible against the C version? Maybe
I have done something wrong while measuring theses times. From my point
of view it should be possible to get such improvements as the code takes
cache alignment into account and also uses the PLD instruction.

I can do some additional measurements tomorrow on two systems (jadecpu
with a 32Bit at 166MHz DDR2 memory and a imx25 based on with 16Bit at 133MHz
LPDDR) and come up with some exact numbers. Maybe you can give some more
hints what and how the improvements of this patch can be measured.

Matthias Weißer