Am 14.02.2013 11:43, schrieb Stefan Hajnoczi: > On Wed, Feb 13, 2013 at 02:21:50PM +0100, Kevin Wolf wrote: >> iozone results with and without this series show significant difference >> for allocating writes: >> >> random random >> KB reclen write rewrite read reread read write >> >> base 65536 8 1727 1945 12546 12539 2449 1836 >> patch 65536 8 1934 1949 12263 12521 2463 1796 >> >> base 1048576 256 22344 38437 105823 106135 37743 32167 >> patch 1048576 256 35989 38542 105231 105994 38301 33036 > > I imagine the benefit is even greater for 4 KB or 8 KB blocksize?
The upper two lines are 8k block size. I suspect that the benefit would be the greatest for misaligned 64k writes, then you have one overlapping allocation for each issued request. Kevin