On Fri, Feb 15, 2008 at 04:07:54PM +0300, Michael Tokarev wrote: > Alasdair G Kergon wrote: > > On Fri, Feb 15, 2008 at 01:08:21PM +0100, Andi Kleen wrote: > >> Implement barrier support for single device DM devices > > > > Thanks. We've got some (more-invasive) dm patches in the works that > > attempt to use flushing to emulate barriers where we can't just > > pass them down like that. > > I wonder if it's worth the effort to try to implement this. DM in theory has some more knowledge for optimization. e.g. for example if it knows that a stream of requests hits only a single device then it can just pass the barriers through again and only flush when there is really a request dependency between different devices. File systems can't do it that fine grained; it's either all or nothing. I don't know if doing it fine grained will much difference in performance though. The only way to find out would be to try it. -Andi -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
