On 9/2/25 6:18 PM, Mike Snitzer wrote: > On Tue, Sep 02, 2025 at 05:27:11PM -0400, Mike Snitzer wrote: >> 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. >> > > The reason for proto=tcp is that I was mounting the Hammerspace > Anvil (metadata server) via 4.2 using tcp. And it is the layout that > the metadata server hands out that directs my 4.2 flexfiles client to > then access the DS over v3 using RDMA. My particular DS server in the > broader testbed has the following in /etc/nfs.conf: > > [general] > > [nfsrahead] > > [exports] > > [exportfs] > > [gssd] > use-gss-proxy = 1 > > [lockd] > > [exportd] > > [mountd] > > [nfsdcld] > > [nfsdcltrack] > > [nfsd] > rdma = y > rdma-port = 20049 > threads = 576 > vers4.0 = n > vers4.1 = n > > [statd] > > [sm-notify] > > And if I instead mount with: > > mount -o vers=3,proto=rdma,port=20049 192.168.0.106:/mnt/hs_nvme13 /test > > And then re-run dt, I don't see any data mismatch: I'm beginning to suspect that NFSv3 isn't the interesting case. For NFSv3 READs, nfsd_iter_read() is always called with @base == 0. NFSv4 READs, on the other hand, set @base to whatever is the current end of the send buffer's .pages array. The checks in nfsd_analyze_read_dio() might reject the use of direct I/O, or it might be that the code is setting up the alignment of the read buffer incorrectly. > dt (j:1 t:1): File System Information: > dt (j:1 t:1): Mounted from device: 192.168.0.106:/mnt/hs_nvme13 > dt (j:1 t:1): Mounted on directory: /test > dt (j:1 t:1): Filesystem type: nfs > dt (j:1 t:1): Filesystem options: 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=192.168.0.106,mountvers=3,mountproto=tcp,local_lock=none,addr=192.168.0.106 > dt (j:1 t:1): Filesystem block size: 1048576 > dt (j:1 t:1): Filesystem free space: 3812019404800 (3635425.000 Mbytes, 3550.220 Gbytes, 3.467 Tbytes) > dt (j:1 t:1): Filesystem total space: 3838875533312 (3661037.000 Mbytes, 3575.231 Gbytes, 3.491 Tbytes) > > So... I think what this means is my "patch 1" _is_ a working > implementation. BUT, for some reason RDMA with pnfs flexfiles is > "unhappy". > > Would seem I get to keep both pieces and need to sort out what's up > with pNFS flexfiles on this particular RDMA testbed. > > I will post v9 of the NFSD DIRECT patchset with "patch 1" folded in to > the misaligned READ patch (5) and some other small fixes/improvements > to the series, probably tomorrow morning. > > Thanks, > Mike -- Chuck Lever
