Hi!
Recently I've decided to give a try to x86_64 version of mine distro
of choice (subject to change).
I prefer using own compiled kernels, so I know that in both x86_32 and
x86_64 modes .configs are very similar to each other.
The first quote is x86_32 kernel's dmesg (2.6.27.6-1khz i686):
[ 0.000000] Linux version 2.6.27.6-1khz
(poige@xxxxxxxxxxxxxxxx) (gcc version 4.2.4)
[ 0.021589] CPU0: AMD Athlon(tm) 64 X2 Dual Core Processor
6000+ stepping 03
[ 0.092818] Total of 2 processors activated (12061.15 BogoMIPS).
[ 0.093095] xor: automatically using best checksumming function: pIII_sse
[ 0.097988] pIII_sse : 9164.000 MB/sec
[ 0.098027] xor: using function: pIII_sse (9164.000 MB/sec
[ 2.392055] raid6: int32x1 1121 MB/s
[ 2.409048] raid6: int32x2 1226 MB/s
[ 2.412224] input: AT Translated Set 2 keyboard as /class/input/input0
[ 2.426040] raid6: int32x4 1191 MB/s
[ 2.443066] raid6: int32x8 882 MB/s
[ 2.460013] raid6: mmxx1 2453 MB/s
[ 2.477014] raid6: mmxx2 4574 MB/s
[ 2.494024] raid6: sse1x1 2441 MB/s
[ 2.511014] raid6: sse1x2 4222 MB/s
[ 2.528013] raid6: sse2x1 4187 MB/s
[ 2.545004] raid6: sse2x2 5562 MB/s
[ 2.545042] raid6: using algorithm sse2x2 (5562 MB/s)
And now follows x86_64:
[ 0.000000] Linux version 2.6.27.6-64_1khz (root@archlive) (gcc
version 4.3.1 (GCC) )
[ 0.019180] CPU0: AMD Athlon(tm) 64 X2 Dual Core Processor
6000+ stepping 03
[ 0.091750] Total of 2 processors activated (12061.66 BogoMIPS).
[ 0.092073] xor: automatically using best checksumming
function: generic_sse
[ 0.096986] generic_sse: 9192.000 MB/sec
[ 0.097024] xor: using function: generic_sse (9192.000 MB/sec)
[ 2.583571] md: raid0 personality registered for level 0
[ 2.583614] md: raid1 personality registered for level 1
[ 2.600025] raid6: int64x1 2722 MB/s
[ 2.617010] raid6: int64x2 3660 MB/s
[ 2.634006] raid6: int64x4 3265 MB/s
[ 2.651012] raid6: int64x8 2593 MB/s
[ 2.668034] raid6: sse2x1 1476 MB/s
[ 2.685021] raid6: sse2x2 2316 MB/s
[ 2.702022] raid6: sse2x4 3175 MB/s
[ 2.702060] raid6: using algorithm sse2x4 (3175 MB/s)
So, there're 2 strange things in those dmesgs. The first one might be
unrelated to Linux RAID but affects it -- have you noticed that in
x86_64, raid6 algorithm is ~ 50 % slower, than in x86_32? Is that due
to not too optimized code for x86_64 mode? And the second -- why is
raid6 using algorithm sse2x4 (3175 MB/s), whereas int64x2 gives
slightly better (~ 15 %) throughput -- 3660 MB/s?
Has anyone on the list similar observations? Can gcc's version
difference affect so much? I doubt that, but I can try build x86_32
with gcc 4.3.1 (as x86_64 was).
--
End of message. Next message?
--
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
