Dan Williams <dan.j.williams@xxxxxxxxx> writes: > The write performance numbers are better than I expected and would seem > to address the concerns raised in the thread "Odd (slow) RAID > performance"[2]. The read performance drop was not expected. However, > the numbers suggest some additional changes to be made to the queuing > model. Have you considered supporting copy-xor in MD for non accelerated RAID? I've been looking at fixing the old dubious slow crufty x86 SSE XOR functions. One thing I discovered is that it seems fairly pointless to make them slower with cache avoidance when most of the data is copied before anyways. I think much more advantage could be gotten by supporting copy-xor because XORing during a copy should be nearly free. On the other hand ext3 write() also uses a cache avoiding copy now and for the XOR it would need to load the data from memory again. Perhaps this could be also optimized somehow (e.g. setting a flag somewhere and using a normal copy for the RAID-5 case) -Andi - 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
