Igor Podlesny wrote: > > 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). > The SSE modes have nicer cache behaviours and are therefore preferred even if they are slower. It is very odd that your SSE2 modes are that much slower in 64-bit mode. It could just be an artifact of the may the test is done (cache anomalies?), but I kind of suspect there is something more fishy going on. The sse2 code in the x1 and x2 case is actually identical between x86-32 and -64 (the x4 case is only available for -64) so it is very strange that you're seeing this kind of effect. -hpa -- 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
