On Sat, 13 Jan 2024 at 17:11, Chuck Lever III <chuck.lever@xxxxxxxxxx> wrote: > > > > > On Jan 13, 2024, at 10:09 AM, Jeff Layton <jlayton@xxxxxxxxxx> wrote: > > > > On Sat, 2024-01-13 at 15:47 +0100, Roland Mainz wrote: > >> > >> On Sat, Jan 13, 2024 at 1:19 AM Dan Shelton <dan.f.shelton@xxxxxxxxx> wrote: > > Is there a problem with that (assuming NFSv4.1 session limits are honored) ? > > Yes: very clearly the client will hit a rather artificial > path length limit. And the limit isn't based on the character > length of the path: the limit is hit much sooner with a path > that is constructed from a series of very short component > names, for instance. > > Good client implementations keep the number of operations per > COMPOUND limited to a small number, and break up operations > like path walks to ensure that the protocol and server > implementation do not impose any kind of application-visible > constraint. This is not "good client implementation", this is bad design to force single operations into smaller pieces. This has drastic implications, and all are BAD: - increased latency, by adding more round trips to complete a single vfs operation. Right now the NFSv4 Linux server implementation already has enough issues with bad latency - increased volume of network traffic - decreased throughput - worker threads have less to do per compound, but the number of compounds goes up. But neither are there more server threads, and the per compound overhead is static, and just multiples with the additional requests This is basically what ruined X11 in the long run. The protocol split everything into little requests, but over 20 years the networks did not scale with the increment in CPU power, making X11 less and less capable over the network. No one added more complex and powerful X11 requests, dooming the X11 performance over network. So the Linux NFSv4 implementation is now doing the same, but at least the protocol has knobs to scale it better. Ced -- Cedric Blancher <cedric.blancher@xxxxxxxxx> [https://plus.google.com/u/0/+CedricBlancher/] Institute Pasteur
