On Thursday, March 03/02/17, 2017 at 14:00:33 +0530, Nicholas A. Bellinger wrote: > Hi Bharat & Co, > > Adding Jenny + Or CC', as I believe they are still the main point people > for iser-target related items at Mellanox. > > On Fri, 2017-02-24 at 14:44 +0530, Potnuri Bharat Teja wrote: > > 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 > > IIRC, this message in iscsi_target_login.c:iscsi_login_zero_tsih_s2() > indicates the initiator presented MRDSL was either not PAGE_SIZED > aligned, or less than PAGE_SIZE.. > > Not sure why this is happening with a MRDSL=16384..? Can you confirm > what MRDSL came across the wire..? Hi Nicholas, Thanks for the reply! I saw the same MRDSL=16384 over the wire. > > This would explain the iw_cxgb4 errors about the receive buffers posted > by target are insufficient for incoming data. > > > 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. > > > > Mmmm. > > > 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. > > > > OK, it sounds like a reasonable approach to always enforce the default > MXDSL=8192 from the target side. > > The issue of ignoring what the initiator sent for MRDSL, and always > enforcing MRDSL=8192 would be OK if the initiator is presenting a MRDSL > larger than 8192, but could be problematic if it is presenting a MRDSL > smaller than 8192. > > So I think the right approach would be: > > - Always use MXDSL = 8192 in iser-target, regardless of what's > configured by targetcli via configfs, et al. > - Always honor MRDSL = 8192 in iser-target, when the initiator presents > a MRDSL >= 8192 during login. > - If the initiator is attempting to present a MRDSL < 8192, fail > the login with ISCSI_LOGIN_STATUS_INIT_ERR Agreed! > > Jenny + Or, WDYT..? -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
