Return-Path: linux-nfs-owner@vger.kernel.org Received: from mx12.netapp.com ([216.240.18.77]:44422 "EHLO mx12.netapp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751727Ab3KOW3z convert rfc822-to-8bit (ORCPT ); Fri, 15 Nov 2013 17:29:55 -0500 From: "Myklebust, Trond" To: Charles Edward Lever CC: Klemens Senn , Linux NFS Mailing List Subject: Re: NFS over RDMA stops working for data larger than 812 Bytes Date: Fri, 15 Nov 2013 22:29:52 +0000 Message-ID: <4673A7C9-3424-48F4-B64C-976EFE16017C@netapp.com> References: <24663A6D-A54A-441B-880E-BB7FD6BBB3F2@oracle.com> In-Reply-To: <24663A6D-A54A-441B-880E-BB7FD6BBB3F2@oracle.com> Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Sender: linux-nfs-owner@vger.kernel.org List-ID: On Nov 15, 2013, at 16:39, Chuck Lever wrote: > Hi Trond- > > Klemens Senn says: >> Hi, >> >> I started setting up NFS over RDMA on a OpenSUSE 12.3 machine using the >> 3.7.10-1.16-default kernel. >> Mounting the NFS share works and getting a file with 812 Bytes succeeds. >> Reading 813 Bytes raises a Input/output error. >> >> The export on the server side is done with >> /data >> 172.16.100.0/24(rw,wdelay,crossmnt,insecure,no_root_squash,no_subtree_check,fsid=0,mountpoint) >> >> Following command is used for mounting the NFSv4 share: >> mount -t nfs -o port=20049,rdma,vers=4.0,timeo=900 172.16.100.2:/ /mnt/ >> >> Testing the client side with older kernels stated that the mount is >> working properly with the 3.4.67 kernel. I continued testing with the >> 3.10.17 kernel and enabled the debug level and noticed the message >> "server cheating in read reply: count 813 > recvd 0" >> >> Here is the syslog output: >> NFS: read(//813_bytes, 262144@0) >> NFS: nfs_readpage (ffffea001db1e898 4096@0) >> NFS: 0 initiated read call (req 0:33/70, 813 bytes @ offset 0) >> RPC: new task initialized, procpid 9881 >> RPC: allocated task ffff88105dacabf8 >> RPC: 1631 __rpc_execute flags=0x1 >> <-- nfs4_setup_sequence status=0 >> RPC: 1631 call_start nfs4 proc READ (async) >> RPC: 1631 call_reserve (status 0) >> RPC: 1631 reserved req ffff88085e641c00 xid 3f6a89a6 >> RPC: 1631 call_reserveresult (status 0) >> RPC: 1631 call_refresh (status 0) >> RPC: 1631 refreshing UNIX cred ffff88087c2108c0 >> RPC: 1631 call_refreshresult (status 0) >> RPC: 1631 call_allocate (status 0) >> RPC: xprt_rdma_allocate: size 684, request 0xffff88084a342000 >> RPC: 1631 call_bind (status 0) >> RPC: 1631 call_connect xprt ffff88085f297000 is connected >> RPC: 1631 call_transmit (status 0) >> RPC: 1631 xprt_prepare_transmit >> RPC: 1631 xprt_cwnd_limited cong = 0 cwnd = 4096 >> RPC: 1631 rpc_xdr_encode (status 0) >> RPC: 1631 marshaling UNIX cred ffff88087c2108c0 >> RPC: 1631 using AUTH_UNIX cred ffff88087c2108c0 to wrap rpc data >> RPC: 1631 xprt_transmit(144) >> RPC: rpcrdma_inline_pullup: pad 0 destp 0xffff88084a3437f0 len 144 >> hdrlen 144 >> RPC: rpcrdma_register_frmr_external: Using frmr ffff88084b612d10 >> to map 1 segments >> RPC: rpcrdma_create_chunks: write chunk elem >> 813@0x87bf95000:0x8a905 (more) >> RPC: rpcrdma_register_frmr_external: Using frmr ffff88084b612d38 >> to map 1 segments >> RPC: rpcrdma_create_chunks: write chunk elem >> 152@0x84a343974:0x8aa01 (last) >> RPC: rpcrdma_marshal_req: write chunk: hdrlen 68 rpclen 144 padlen >> 0 headerp 0xffff88084a343100 base 0xffff88084a343760 lkey 0x8000 >> RPC: rpcrdma_event_process: event rep ffff88084b612d10 status 0 >> opcode 8 length 4294936584 >> RPC: rpcrdma_event_process: event rep ffff88084b612d38 status 0 >> opcode 8 length 4294936584 >> RPC: 1631 xmit complete >> RPC: 1631 sleep_on(queue "xprt_pending" time 4296115067) >> RPC: 1631 added to queue ffff88085f297258 "xprt_pending" >> RPC: 1631 setting alarm for 90000 ms >> RPC: wake_up_first(ffff88085f297190 "xprt_sending") >> RPC: rpcrdma_event_process: event rep ffff88085e8bf000 status 0 >> opcode 80 length 128 >> RPC: rpcrdma_reply_handler: reply 0xffff88085e8bf000 completes >> request 0xffff88084a342000 >> RPC request 0xffff88085e641c00 xid 0xa6896a3f >> RPC: rpcrdma_count_chunks: chunk 813@0x87bf95000:0x8a905 >> RPC: rpcrdma_count_chunks: chunk 3@0x84a343974:0x8aa01 >> RPC: rpcrdma_inline_fixup: srcp 0xffff88085e8bf0a4 len 60 hdrlen 60 >> RPC: rpcrdma_reply_handler: xprt_complete_rqst(0xffff88085f297000, >> 0xffff88085e641c00, 876) >> RPC: 1631 xid 3f6a89a6 complete (876 bytes received) >> RPC: 1631 __rpc_wake_up_task (now 4296115067) >> RPC: 1631 disabling timer >> RPC: 1631 removed from queue ffff88085f297258 "xprt_pending" >> RPC: __rpc_wake_up_task done >> RPC: 1631 __rpc_execute flags=0x801 >> RPC: 1631 call_status (status 876) >> RPC: 1631 call_decode (status 876) >> RPC: 1631 validating UNIX cred ffff88087c2108c0 >> RPC: 1631 using AUTH_UNIX cred ffff88087c2108c0 to unwrap rpc data >> NFS: server cheating in read reply: count 813 > recvd 0 >> RPC: 1631 call_decode result 0 >> NFS: nfs_readpage_result: 1631, (status 0) >> --> nfs4_read_done >> >> Adding other debug prints to the kernel module told me that >> buf->page_len is set to 0 in xdr_align_pages (in file net/sunrpc/xdr.c). >> Comparing this piece of code with older kernel versions showed that the >> comparison with buf->page_len was introduces in kernel 3.7. >> By disabling this check the file transfer seems to work. >> >> Here is the patch for kernel 3.10.17: >> >> --- net/sunrpc/xdr.c 2013-10-18 19:44:19.000000000 +0200 >> +++ net/sunrpc/xdr_new.c 2013-11-08 14:06:00.241217773 +0100 >> @@ -747,7 +747,7 @@ >> nwords = xdr->nwords; >> len = nwords << 2; >> } >> - if (buf->page_len <= len) >> + if (buf->page_len && buf->page_len <= len) >> len = buf->page_len; >> else if (nwords < xdr->nwords) { >> /* Truncate page data and move it into the tail */ >> >> >> Can you please tell me which entity sets (or does not set) the total >> length (buf->page_len) after receiving the data from the RDMA_SEND >> operation from the server? >> >> Please advise >> >> Klemens > > Comparing xdr_align_pages() before commit a11a2bf4 and afterwords, it appears that it no longer handles cases where buf->page_len == 0 the same way it used to. xdr_align_pages() would never return zero unless xdr->nwords was zero. Why would the buf->page_len == 0 in a READ call? Has RDMA been relying on some kind of undocumented behaviour? Trond