On Tue, 6 Aug 2013 09:34:07 -0400 "J. Bruce Fields" <bfields@xxxxxxxxxxxx> wrote: > On Tue, Aug 06, 2013 at 07:14:28AM -0400, Jeff Layton wrote: > > On Tue, 6 Aug 2013 11:02:09 +0000 > > Larry Keegan <lk@xxxxxxxxxxxxxxx> wrote: > > > These figures seem reasonable for a single SATA HDD in concert > > > with dmcrypt. Whilst I expected some degradation from exporting > > > and mounting sync, I have to say that I'm truly flabbergasted by > > > the difference between the sync and async figures. I can't help > > > but think I am still suffering from some sort of configuration > > > problem. Do the numbers from the NFS client seem unreasonable? > > > > > > > That's expected. Performance is the tradeoff for tight cache > > coherency. > > > > With -o sync, each write() sycall requires a round trip to the > > server. They don't get batched and you can't issue them in > > parallel. That has a terrible effect on write performance. > > Note also mounting -osync and exporting with the "sync" export option > are entirely different things. > > The defaults are what you want (async mount option, sync export > option) unless you've thought hard about it. This is especially true > on the server, since the "async" export option make it skip > committing data to disk even when the protocol mandates it. Righto. This makes sense. After a brief pause I'll see if I can tickle the ESTALE problem under NFS 4. With many thanks. Yours, Larry. -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
