On Wednesday May 24, davidsen@xxxxxxx wrote: > Mark Hahn wrote: > > >>I just dd'ed a 700MB iso to /dev/null, dd returned 33MB/s. > >>Isn't that a little slow? > >> > >> > > > >what bs parameter did you give to dd? it should be at least 3*chunk > >(probably 3*64k if you used defaults.) > > > > I would expect readahead to make this unproductive. Mind you, I didn't > say it is, but I can't see why not. There was a problem with data going > through stripe cache when it didn't need to, but I thought that was fixed. > > Neil? Am I an optimist? Probably.... You are write about readahead - it should make the difference in block size irrelevant. You are wrong about the problem of reading through the cache being fixed. It hasn't yet. We still read through the cache. However that shouldn't cause more than a 10% speed reduction, and 33MB/s sounds like more than 10% down. NeilBrown - 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
