On Sat, Apr 25, 2009 at 11:20:24AM +1000, npiggin@xxxxxxx wrote: > This patch speeds up lmbench lat_mmap test by about another 2% after the > first patch. > > Before: > avg = 462.286 > std = 5.46106 > > After: > avg = 453.12 > std = 9.58257 > > (50 runs of each, stddev gives a reasonable confidence) > > It does this by introducing mnt_clone_write, which avoids some heavyweight > operations of mnt_want_write if called on a vfsmount which we know already > has a write count; and mnt_want_write_file, which can call mnt_clone_write > if the file is open for write. > > After these two patches, mnt_want_write and mnt_drop_write go from 7% on > the profile down to 1.3% (including mnt_clone_write). NAK in this form; nested mnt_want_write() *CAN* fail (note the check for superblock itself being r/o). Make you mnt_clone_write() returning int and doing that superblock check, and I'm OK with it. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
