From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 53B94C4363C for ; Wed, 7 Oct 2020 03:36:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 13503208C3 for ; Wed, 7 Oct 2020 03:36:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726719AbgJGDgr (ORCPT ); Tue, 6 Oct 2020 23:36:47 -0400 Received: from stargate.chelsio.com ([12.32.117.8]:56409 "EHLO stargate.chelsio.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725981AbgJGDgr (ORCPT ); Tue, 6 Oct 2020 23:36:47 -0400 Received: from localhost (pvp1.blr.asicdesigners.com [10.193.80.26]) by stargate.chelsio.com (8.13.8/8.13.8) with ESMTP id 0973aLTN019828; Tue, 6 Oct 2020 20:36:22 -0700 Date: Wed, 7 Oct 2020 09:06:21 +0530 From: Krishnamraju Eraparaju To: Max Gurtovoy Cc: Sagi Grimberg , linux-rdma@vger.kernel.org, Potnuri Bharat Teja , Max Gurtovoy Subject: Re: reduce iSERT Max IO size Message-ID: <20201007033619.GA11425@chelsio.com> References: <20200922104424.GA18887@chelsio.com> <07e53835-8389-3e07-6976-505edbd94f2a@grimberg.me> <20201002171007.GA16636@chelsio.com> <4d0b1a3f-2980-c7ed-ef9a-0ed6a9c87a69@grimberg.me> <20201003033644.GA19516@chelsio.com> <4391e240-5d6d-fb59-e6fb-e7818d1d0bd2@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4391e240-5d6d-fb59-e6fb-e7818d1d0bd2@nvidia.com> User-Agent: Mutt/1.5.21 (2010-09-15) Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org 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 > >>Tested-by: Krishnamraju Eraparaju > >>Signed-off-by: Max Gurtovoy > >>-- > >> > >>> > >>>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?