On Tue, Sep 02, 2025 at 05:16:10PM -0400, Chuck Lever wrote: > On 9/2/25 5:06 PM, Mike Snitzer wrote: > > On Tue, Sep 02, 2025 at 01:59:12PM -0400, Chuck Lever wrote: > >> On 9/2/25 11:56 AM, Chuck Lever wrote: > >>> On 8/30/25 1:38 PM, Mike Snitzer wrote: > >> > >>>> dt (j:1 t:1): File System Information: > >>>> dt (j:1 t:1): Mounted from device: 192.168.0.105:/hs_test > >>>> dt (j:1 t:1): Mounted on directory: /mnt/hs_test > >>>> dt (j:1 t:1): Filesystem type: nfs4 > >>>> dt (j:1 t:1): Filesystem options: rw,relatime,vers=4.2,rsize=1048576,wsize=1048576,namlen=255,hard,fatal_neterrors=none,proto=tcp,nconnect=16,port=20491,timeo=600,retrans=2,sec=sys,clientaddr=192.168.0.106,local_lock=none,addr=192.168.0.105 > >>> > >>> I haven't been able to reproduce a similar failure in my lab with > >>> NFSv4.2 over RDMA with FDR InfiniBand. I've run dt 6-7 times, all > >>> successful. Also, for shit giggles, I tried the fsx-based subtests in > >>> fstests, no new failures there either. The export is xfs on an NVMe > >>> add-on card; server uses direct I/O for READ and page cache for WRITE. > >>> > >>> Notice the mount options for your test run: "proto=tcp" and > >>> "nconnect=16". Even if your network fabric is RoCE, "proto=tcp" will > >>> not use RDMA at all; it will use bog standard TCP/IP on your ultra > >>> fast Ethernet network. > >>> > >>> What should I try next? I can apply 2/2 or add "nconnect" or move the > >>> testing to my RoCE fabric after lunch and keep poking at it. > > > > Hmm, I'll have to check with the Hammerspace performance team to > > understand how RDMA used if the client mount has proto=tcp. > > > > Certainly surprising, thanks for noticing/reporting this aspect. > > > > I also cannot reproduce on a normal tcp mount and testbed. This > > frankenbeast of a fast "RDMA" network that is misconfigured to use > > proto=tcp is the only testbed where I've seen this dt data mismatch. > > > >>> Or, I could switch to TCP. Suggestions welcome. > >> > >> The client is not sending any READ procedures/operations to the server. > >> The following is NFSv3 for clarity, but NFSv4.x results are similar: > >> > >> nfsd-1669 [003] 1466.634816: svc_process: > >> addr=192.168.2.67 xid=0x7b2a6274 service=nfsd vers=3 proc=NULL > >> nfsd-1669 [003] 1466.635389: svc_process: > >> addr=192.168.2.67 xid=0x7d2a6274 service=nfsd vers=3 proc=FSINFO > >> nfsd-1669 [003] 1466.635420: svc_process: > >> addr=192.168.2.67 xid=0x7e2a6274 service=nfsd vers=3 proc=PATHCONF > >> nfsd-1669 [003] 1466.635451: svc_process: > >> addr=192.168.2.67 xid=0x7f2a6274 service=nfsd vers=3 proc=GETATTR > >> nfsd-1669 [003] 1466.635486: svc_process: > >> addr=192.168.2.67 xid=0x802a6274 service=nfsacl vers=3 proc=NULL > >> nfsd-1669 [003] 1466.635558: svc_process: > >> addr=192.168.2.67 xid=0x812a6274 service=nfsd vers=3 proc=FSINFO > >> nfsd-1669 [003] 1466.635585: svc_process: > >> addr=192.168.2.67 xid=0x822a6274 service=nfsd vers=3 proc=GETATTR > >> nfsd-1669 [003] 1470.029208: svc_process: > >> addr=192.168.2.67 xid=0x832a6274 service=nfsd vers=3 proc=ACCESS > >> nfsd-1669 [003] 1470.029255: svc_process: > >> addr=192.168.2.67 xid=0x842a6274 service=nfsd vers=3 proc=LOOKUP > >> nfsd-1669 [003] 1470.029296: svc_process: > >> addr=192.168.2.67 xid=0x852a6274 service=nfsd vers=3 proc=FSSTAT > >> nfsd-1669 [003] 1470.039715: svc_process: > >> addr=192.168.2.67 xid=0x862a6274 service=nfsacl vers=3 proc=GETACL > >> nfsd-1669 [003] 1470.039758: svc_process: > >> addr=192.168.2.67 xid=0x872a6274 service=nfsd vers=3 proc=CREATE > >> nfsd-1669 [003] 1470.040091: svc_process: > >> addr=192.168.2.67 xid=0x882a6274 service=nfsd vers=3 proc=WRITE > >> nfsd-1669 [003] 1470.040469: svc_process: > >> addr=192.168.2.67 xid=0x892a6274 service=nfsd vers=3 proc=GETATTR > >> nfsd-1669 [003] 1470.040503: svc_process: > >> addr=192.168.2.67 xid=0x8a2a6274 service=nfsd vers=3 proc=ACCESS > >> nfsd-1669 [003] 1470.041867: svc_process: > >> addr=192.168.2.67 xid=0x8b2a6274 service=nfsd vers=3 proc=FSSTAT > >> nfsd-1669 [003] 1470.042109: svc_process: > >> addr=192.168.2.67 xid=0x8c2a6274 service=nfsd vers=3 proc=REMOVE > >> > >> So I'm probably missing some setting on the reproducer/client. > >> > >> /mnt from klimt.ib.1015granger.net:/export/fast > >> Flags: rw,relatime,vers=3,rsize=1048576,wsize=1048576,namlen=255,hard, > >> fatal_neterrors=none,proto=rdma,port=20049,timeo=600,retrans=2, > >> sec=sys,mountaddr=192.168.2.55,mountvers=3,mountproto=tcp, > >> local_lock=none,addr=192.168.2.55 > >> > >> Linux morisot.1015granger.net 6.15.10-100.fc41.x86_64 #1 SMP > >> PREEMPT_DYNAMIC Fri Aug 15 14:55:12 UTC 2025 x86_64 GNU/Linux > > > > If you're using LOCALIO (client on server) that'd explain your not > > seeing any READs coming over the wire to NFSD. > > > > I've made sure to disable LOCALIO on my client, with: > > echo N > /sys/module/nfs/parameters/localio_enabled > > I am testing with a physically separate client and server, so I believe > that LOCALIO is not in play. I do see WRITEs. And other workloads (in > particular "fsx -Z <fname>") show READ traffic and I'm getting the > new trace point to fire quite a bit, and it is showing misaligned > READ requests. So it has something to do with dt. OK, yeah I figured you weren't doing loopback mount, only thing that came to mind for you not seeing READ like expected. I haven't had any problems with dt not driving READs to NFSD... You'll certainly need to see READs in order for NFSD's new misaligned DIO READ handling to get tested. > If I understand your two patches correctly, they are still pulling a > page from the end of rq_pages to do the initial pad page. That, I > think, is a working implementation, not the failing one. Patch 1 removes the use of a separate page, instead using the very first page of rq_pages for the "start_extra" (or "front_pad) page for the misaligned DIO READ. And with that my dt testing fails with data mismatch like I shared. So patch 1 is failing implementation (for me on the "RDMA" system I'm testing on). Patch 2 then switches to using a rq_pages page _after_ the memory that would normally get used as the READ payload memory to service the READ. So patch 2 is a working implementation. > EOD -- will continue tomorrow. Ack.
