From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bart Van Assche Subject: Re: Testing for RDMA with ib_srp: Failed to map data (-12) with max_sectors_kb=4096 and buffered I/O with 4MB writes Date: Thu, 21 Apr 2016 11:48:24 -0700 Message-ID: <57192078.8030402@sandisk.com> References: <559411025.30902774.1461207472544.JavaMail.zimbra@redhat.com> <571918A5.8050504@grimberg.me> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <571918A5.8050504-NQWnxTmZq1alnMjI0IkVqw@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Sagi Grimberg , Laurence Oberman , linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-rdma@vger.kernel.org On 04/21/2016 11:15 AM, Sagi Grimberg wrote: >> I am still on my quest for getting 4MB buffered writes to be stable to >> RDMA SRP targets. >> Lots of testing has been performed here with EDR 100 back to back >> connections using >> mellanox ConnectX-4 with mlx5_ib, an dthe ib_srp* drivers on target >> server and client. >> >> In summary: >> setting max_sectors_kb=4096 and running DIRECT_IO is solid as a rock >> setting max_sectors_kb=2048 and running buffered 4MB writes to an FS >> on a multipath is rock solid >> >> However: >> setting max_sectors_kb=4096 and running buffered I/O sees serious >> mapping issues. >> >> >> I have isolated the failure and call flow to this >> >> srp_queuecommand >> srp_map_data(scmnd, ch, req); >> srp_map_idb >> ret = srp_map_finish_fr(&state, req, ch, 1); >> >> >> The -12 is returned by srp_map_finish_fr() and fed back to fail with >> ib_srp: Failed to map data (-12) > > Can you print out how many FRs we used at this point? > > state->nmdesc? Hello Sagi and Laurence, Since the SRP initiator can use multiple MRs per I/O it can happen that (temporarily) no MRs are available if both max_sectors and the queue depth are high enough. I'm working on a patch to prevent that this can happen. Bart. -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html