On Sunday, October 10/04/20, 2020 at 00:45:26 +0300, Max Gurtovoy wrote: > > On 10/3/2020 6:36 AM, Krishnamraju Eraparaju wrote: > >On Friday, October 10/02/20, 2020 at 13:29:30 -0700, Sagi Grimberg wrote: > >>>Hi Sagi & Max, > >>> > >>>Any update on this? > >>>Please change the max IO size to 1MiB(256 pages). > >>I think that the reason why this was changed to handle the worst case > >>was in case there are different capabilities on the initiator and the > >>target with respect to number of pages per MR. There is no handshake > >>that aligns expectations. > >But, the max pages per MR supported by most adapters is around 256 pages > >only. > >And I think only those iSER initiators, whose max pages per MR is 4096, > >could send 16MiB sized IOs, am I correct? > > If the initiator can send 16MiB, we must make sure the target is > capable to receive it. I think max IO size, at iSER initiator, depends on "max_fast_reg_page_list_len". currently, below are the supported "max_fast_reg_page_list_len" of various iwarp drivers: iw_cxgb4: 128 pages Softiwarp: 256 pages i40iw: 512 pages qedr: couldn't find. For iwarp case, if 512 is the max pages supported by all iwarp drivers, then provisioning a gigantic MR pool at target(to accommodate never used 16MiB IO) wouldn't be a overkill? > > > > >>If we revert that it would restore the issue that you reported in the > >>first place: > >> > >>-- > >>IB/isert: allocate RW ctxs according to max IO size > >I don't see the reported issue after reducing the IO size to 256 > >pages(keeping all other changes of this patch intact). > >That is, "attr.cap.max_rdma_ctxs" is now getting filled properly with > >"rdma_rw_mr_factor()" related changes, I think. > > > >Before this change "attr.cap.max_rdma_ctxs" was hardcoded with > >128(ISCSI_DEF_XMIT_CMDS_MAX) pages, which is very low for single target > >and muli-luns case. > > > >So reverting only ISCSI_ISER_MAX_SG_TABLESIZE macro to 256 doesn't cause the > >reported issue. > > > >Thanks, > >Krishnam Raju. > >>Current iSER target code allocates MR pool budget based on queue size. > >>Since there is no handshake between iSER initiator and target on max IO > >>size, we'll set the iSER target to support upto 16MiB IO operations and > >>allocate the correct number of RDMA ctxs according to the factor of MR's > >>per IO operation. This would guaranty sufficient size of the MR pool for > >>the required IO queue depth and IO size. > >> > >>Reported-by: Krishnamraju Eraparaju <krishna2@xxxxxxxxxxx> > >>Tested-by: Krishnamraju Eraparaju <krishna2@xxxxxxxxxxx> > >>Signed-off-by: Max Gurtovoy <maxg@xxxxxxxxxxxx> > >>-- > >> > >>> > >>>Thanks, > >>>Krishnam Raju. > >>>On Wednesday, September 09/23/20, 2020 at 01:57:47 -0700, Sagi Grimberg wrote: > >>>>>Hi, > >>>>> > >>>>>Please reduce the Max IO size to 1MiB(256 pages), at iSER Target. > >>>>>The PBL memory consumption has increased significantly after increasing > >>>>>the Max IO size to 16MiB(with commit:317000b926b07c). > >>>>>Due to the large MR pool, the max no.of iSER connections(On one variant > >>>>>of Chelsio cards) came down to 9, before it was 250. > >>>>>NVMe-RDMA target also uses 1MiB max IO size. > >>>>Max, remind me what was the point to support 16M? Did this resolve > >>>>an issue?
