On Mon, Nov 29, 2021 at 07:03:12PM +0000, Chuck Lever III wrote: > Hello Dai! > > > > On Nov 29, 2021, at 1:32 PM, Dai Ngo <dai.ngo@xxxxxxxxxx> wrote: > > > > > > On 11/29/21 9:30 AM, J. Bruce Fields wrote: > >> On Mon, Nov 29, 2021 at 09:13:16AM -0800, dai.ngo@xxxxxxxxxx wrote: > >>> Hi Bruce, > >>> > >>> On 11/21/21 7:04 PM, dai.ngo@xxxxxxxxxx wrote: > >>>> On 11/17/21 4:34 PM, J. Bruce Fields wrote: > >>>>> On Wed, Nov 17, 2021 at 01:46:02PM -0800, dai.ngo@xxxxxxxxxx wrote: > >>>>>> On 11/17/21 9:59 AM, dai.ngo@xxxxxxxxxx wrote: > >>>>>>> On 11/17/21 6:14 AM, J. Bruce Fields wrote: > >>>>>>>> On Tue, Nov 16, 2021 at 03:06:32PM -0800, dai.ngo@xxxxxxxxxx wrote: > >>>>>>>>> Just a reminder that this patch is still waiting for your review. > >>>>>>>> Yeah, I was procrastinating and hoping yo'ud figure out the pynfs > >>>>>>>> failure for me.... > >>>>>>> Last time I ran 4.0 OPEN18 test by itself and it passed. I will run > >>>>>>> all OPEN tests together with 5.15-rc7 to see if the problem you've > >>>>>>> seen still there. > >>>>>> I ran all tests in nfsv4.1 and nfsv4.0 with courteous and non-courteous > >>>>>> 5.15-rc7 server. > >>>>>> > >>>>>> Nfs4.1 results are the same for both courteous and > >>>>>> non-courteous server: > >>>>>>> Of those: 0 Skipped, 0 Failed, 0 Warned, 169 Passed > >>>>>> Results of nfs4.0 with non-courteous server: > >>>>>>> Of those: 8 Skipped, 1 Failed, 0 Warned, 577 Passed > >>>>>> test failed: LOCK24 > >>>>>> > >>>>>> Results of nfs4.0 with courteous server: > >>>>>>> Of those: 8 Skipped, 3 Failed, 0 Warned, 575 Passed > >>>>>> tests failed: LOCK24, OPEN18, OPEN30 > >>>>>> > >>>>>> OPEN18 and OPEN30 test pass if each is run by itself. > >>>>> Could well be a bug in the tests, I don't know. > >>>> The reason OPEN18 failed was because the test timed out waiting for > >>>> the reply of an OPEN call. The RPC connection used for the test was > >>>> configured with 15 secs timeout. Note that OPEN18 only fails when > >>>> the tests were run with 'all' option, this test passes if it's run > >>>> by itself. > >>>> > >>>> With courteous server, by the time OPEN18 runs, there are about 1026 > >>>> courtesy 4.0 clients on the server and all of these clients have opened > >>>> the same file X with WRITE access. These clients were created by the > >>>> previous tests. After each test completed, since 4.0 does not have > >>>> session, the client states are not cleaned up immediately on the > >>>> server and are allowed to become courtesy clients. > >>>> > >>>> When OPEN18 runs (about 20 minutes after the 1st test started), it > >>>> sends OPEN of file X with OPEN4_SHARE_DENY_WRITE which causes the > >>>> server to check for conflicts with courtesy clients. The loop that > >>>> checks 1026 courtesy clients for share/access conflict took less > >>>> than 1 sec. But it took about 55 secs, on my VM, for the server > >>>> to expire all 1026 courtesy clients. > >>>> > >>>> I modified pynfs to configure the 4.0 RPC connection with 60 seconds > >>>> timeout and OPEN18 now consistently passed. The 4.0 test results are > >>>> now the same for courteous and non-courteous server: > >>>> > >>>> 8 Skipped, 1 Failed, 0 Warned, 577 Passed > >>>> > >>>> Note that 4.1 tests do not suffer this timeout problem because the > >>>> 4.1 clients and sessions are destroyed after each test completes. > >>> Do you want me to send the patch to increase the timeout for pynfs? > >>> or is there any other things you think we should do? > >> I don't know. > >> > >> 55 seconds to clean up 1026 clients is about 50ms per client, which is > >> pretty slow. I wonder why. I guess it's probably updating the stable > >> storage information. Is /var/lib/nfs/ on your server backed by a hard > >> drive or an SSD or something else? > > > > My server is a virtualbox VM that has 1 CPU, 4GB RAM and 64GB of hard > > disk. I think a production system that supports this many clients should > > have faster CPUs, faster storage. > > > >> > >> I wonder if that's an argument for limiting the number of courtesy > >> clients. > > > > I think we might want to treat 4.0 clients a bit different from 4.1 > > clients. With 4.0, every client will become a courtesy client after > > the client is done with the export and unmounts it. > > It should be safe for a server to purge a client's lease immediately > if there is no open or lock state associated with it. > > When an NFSv4.0 client unmounts, all files should be closed at that > point, so the server can wait for the lease to expire and purge it > normally. Or am I missing something? Makes sense to me! > > Since there is > > no destroy session/client with 4.0, the courteous server allows the > > client to be around and becomes a courtesy client. So after awhile, > > even with normal usage, there will be lots 4.0 courtesy clients > > hanging around and these clients won't be destroyed until 24hrs > > later, or until they cause conflicts with other clients. > > > > We can reduce the courtesy_client_expiry time for 4.0 clients from > > 24hrs to 15/20 mins, enough for most network partition to heal?, > > or limit the number of 4.0 courtesy clients. Or don't support 4.0 > > clients at all which is my preference since I think in general users > > should skip 4.0 and use 4.1 instead. I'm also totally fine with leaving out 4.0, at least to start. --b.
