> On Aug 25, 2024, at 9:56 PM, NeilBrown <neilb@xxxxxxx> wrote: > > On Sat, 24 Aug 2024, Mike Snitzer wrote: >> + >> +6. Why is having the client perform a server-side file OPEN, without >> + using RPC, beneficial? Is the benefit pNFS specific? >> + >> + Avoiding the use of XDR and RPC for file opens is beneficial to >> + performance regardless of whether pNFS is used. However adding a >> + requirement to go over the wire to do an open and/or close ends up >> + negating any benefit of avoiding the wire for doing the I/O itself >> + when we’re dealing with small files. There is no benefit to replacing >> + the READ or WRITE with a new open and/or close operation that still >> + needs to go over the wire. > > I don't think the above is correct. I struggled with this text too. I thought the reason we want a server-side file OPEN is so that proper access authorization, same as would be done on a remote access, can be done. > The current code still does a normal NFSv4 OPEN or NFSv3 GETATTR when > then client opens a file. Only the READ/WRITE/COMMIT operations are > avoided. > > While I'm not advocating for an over-the-wire request to map a > filehandle to a struct nfsd_file*, I don't think you can convincingly > argue against it without concrete performance measurements. > > NeilBrown -- Chuck Lever
