On Mon, 28 Jul 2008 16:56:37 +1000 Nick Piggin <nickpiggin@xxxxxxxxxxxx> wrote: > On Monday 28 July 2008 16:51, Andrew Morton wrote: > > On Mon, 28 Jul 2008 13:34:12 +0900 Hisashi Hifumi > <hifumi.hisashi@xxxxxxxxxxxxx> wrote: > > > Hi > > > > > > >> > Are there significant numbers of people using block size < page size > > > >> > in situations where performance is important and significantly > > > >> > improved by this patch? Can you give any performance numbers to > > > >> > illustrate perhaps? > > > >> > > > >> With XFS lots of people use 4k blocksize filesystems on ia64 systems > > > >> with 16k pages, so an optimization like this would be useful. > > > > > > > >As Nick says, we really should have some measurement results which > > > >confirm this theory. Maybe we did do some but they didn't find theor > > > >way into the changelog. > > > > > > > >I've put the patch on hold until this confirmation data is available. > > > > > > I've got some performance number. > > > I wrote a benchmark program and got result number with this program. > > > This benchmark do: > > > 1, mount and open a test file. > > > 2, create a 512MB file. > > > 3, close a file and umount. > > > 4, mount and again open a test file. > > > 5, pwrite randomly 300000 times on a test file. offset is aligned by IO > > > size(1024bytes). 6, measure time of preading randomly 100000 times on a > > > test file. > > > > > > The result was: > > > 2.6.26 > > > 330 sec > > > > > > 2.6.26-patched > > > 226 sec > > > > > > Arch:i386 > > > Filesystem:ext3 > > > Blocksize:1024 bytes > > > Memory: 1GB > > > > > > On ext3/4, a file is written through buffer/block. So random read/write > > > mixed workloads or random read after random write workloads are optimized > > > with this patch under pagesize != blocksize environment. This test result > > > showed this. > > Yeah, thanks for the numbers. > > > > OK, thanks. Those are pretty nice numbers for what is probably a > > fairly common workload. > > What kind of workloads does this kind of thing? Various databases? (confused). More likely pattern is 8k IOs with 16k pagesize or thereabouts. -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
