On 2012-12-03 18:09, Hiroyuki Yamada wrote: > Sorry for update. > I figured it out. > It's from ext3's indirect block mapping. > There is one mapping block in each 1024 blocks, > so accessing a large file randomly has high chance of accessing the > mapping block and the requested block. > > Ext4 has different and more efficient addressing called extent (tree), and > we can avoid the issue. Ah, yes that makes sense. I thought we were talking about extra writes, but it seems I misread the log since it clearly states FROM_DEVICE transfers. -- Jens Axboe -- To unsubscribe from this list: send the line "unsubscribe fio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
