On Thu, 15 Nov 2007 22:47:40 -0500 Wendy Cheng <wcheng@xxxxxxxxxx> wrote: > Andrew Morton wrote: > > >On Fri, 16 Nov 2007 11:47:27 +0900 Hisashi Hifumi <hifumi.hisashi@xxxxxxxxxxxxx> wrote: > > > > > > > >>Currently fdatasync is identical to fsync in ext3,4. > >>I think fdatasync should skip journal flush in data=ordered and data=writeback mode > >>because this syscall is not required to synchronize the metadata. > >> > >> > > > >I suppose so. Although one wonders what earthly point there is in syncing > >a file's data if we haven't yet written out the metadata which is required > >for locating that data. > > > >IOW, fdatasync() is only useful if the application knows that it is overwriting > >already-instantiated blocks. > > > >In which case it might as well have used fsync(). For ext2-style filesystems, > >anyway. > > > >hm. It needs some thought. > > > > > > > > There are non-trivial amount of performance critical programs, > particularly in financial application segment ported from legacy UNIX > platforms, know the difference between fsync() and fdatasync(). Those > can certainly take advantages of this separation. Don't underestimate > the talents of these application programmers. > If they're that good, they'll be using sync_file_range() ;) - 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
