you are correct. man page says "..untill data has been physically written to the underlying storage". missed that one. thank you dave On Tue, Apr 12, 2011 at 12:52 PM, Dave Chinner <david@xxxxxxxxxxxxx> wrote: > On Tue, Apr 12, 2011 at 10:58:53AM +0300, Raz wrote: >> Christoph Hello >> I am testing 2.6.38 with AIM benchmark. >> I compared 2.6.38 to 2.6.27 and I noticed that 2.6.27 is much better >> than 2.6.38 hwhen >> doing sync random writes test over an xfs regular file over native >> Linux partition on top common sata disk. >> I git bisected the problem and I reached this SHA1: >> commit 13e6d5cdde0e785aa943810f08b801cadd0935df >> Author: Christoph Hellwig <hch@xxxxxx> >> Date: Mon Aug 31 21:00:31 2009 -0300 >> >> xfs: merge fsync and O_SYNC handling >> >> The guarantees for O_SYNC are exactly the same as the ones we need to >> make for an fsync call (and given that Linux O_SYNC is O_DSYNC the >> equivalent is fdadatasync, but we treat both the same in XFS), except >> with a range data writeout. Jan Kara has started unifying these two >> path for filesystems using the generic helpers, and I've started to >> look at XFS. >> ... >> >> >> The bellow two tests presents the how different performance is before and patch: >> #test 16) bisect 11 >> ------------------------------------------------------------------------------------------------------------ >> Test Test Elapsed Iteration Iteration Operation >> Number Name Time (sec) Count Rate (loops/sec) Rate (ops/sec) >> ------------------------------------------------------------------------------------------------------------ >> 1 sync_disk_rw 30.71 19 0.61869 1583.85 >> Sync Random Disk Writes (K)/second >> ------------------------------------------------------------------------------------------------------------ > > That's clearly showing that your sync writes are not hitting the > disk. IOWs, the sync writes are not synchronous at all. There is > no way a single SATA drive can do >1500 writes to stable storage > per second. > > IOWs, before this fix, sync writes were broken on your hardware. > >> #test 17 ) bisect 12 >> ------------------------------------------------------------------------------------------------------------ >> 1 sync_disk_rw 69.05 1 0.01448 37.07 >> Sync Random Disk Writes (K)/second >> ------------------------------------------------------------------------------------------------------------ > > And that's pretty tpyical for a SATA drive where sync writes are > actually hitting the platter correctly. > > Cheers, > > Dave. > -- > Dave Chinner > david@xxxxxxxxxxxxx > _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
