From mboxrd@z Thu Jan 1 00:00:00 1970 From: Potnuri Bharat Teja Subject: [Query] iSER-Target: QP errors observed on increasing MaxXmitDataSegmentLength to 16384 (default = 8192) Date: Fri, 24 Feb 2017 14:44:56 +0530 Message-ID: <20170224091455.GA11766@chelsio.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: sagi-NQWnxTmZq1alnMjI0IkVqw@public.gmane.org, nab-IzHhD5pYlfBP7FQvKIMDCQ@public.gmane.org Cc: linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, target-devel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, swise-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org, rajur-ut6Up61K2wZBDgjK7y7TUQ@public.gmane.org List-Id: linux-rdma@vger.kernel.org Hi Sagi/Nicholas, When tried changing the MaxXmitDataSegmentLength to 16384 (default = 8192), by changing it from targetcli on target and iscsd.conf on initiator, I observe the following errors. cxgb4 0000:06:00.4: AE qpid 1024 opcode 3 status 0x6 type 0 len 0x5c wrid.hi 0x0 wrid.lo 0x136 isert: isert_qp_event_callback: QP access error (3): conn ffff8807da7b6000 Aligning ISER MaxRecvDataSegmentLength: 4096 down to PAGE_SIZE cxgb4 0000:06:00.4: AE qpid 1026 opcode 3 status 0x6 type 0 len 0x5c wrid.hi 0x0 wrid.lo 0x2 isert: isert_qp_event_callback: QP access error (3): conn ffff88053a2ee000 >>From the error status of iw_cxgb4 the receive buffers posted by target are unsufficient for the incoming data to be placed/DMAed by the HW/adapter. Apparently, from the iSER-target code the rx buffers are acclocated for a fixed size of 8192. from isert_alloc_rx_descriptors() in drivers/infiniband/ulp/isert/ib_isert.c rx_sg->length = ISER_RX_PAYLOAD_SIZE; I confirmed the same by increasing the ISER_RX_PAYLOAD_SIZE to 16384 and the errors arent seen. As far as i could see, from the iSER target code, MaxXmitDataSegmentLength should not be changed according to the targetcli/openiscsi parameters and should countinue based on iSER specific Initiator/targetrecvdatasegmentlength and so does the MaxrecvDatasegmentLength. Please let me know if my observations are right and what could be done to fix this. Thanks for your time. Bharat. -- 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