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 A2ECFC4363C for ; Sat, 3 Oct 2020 03:37:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5C01F2078A for ; Sat, 3 Oct 2020 03:37:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725801AbgJCDhC (ORCPT ); Fri, 2 Oct 2020 23:37:02 -0400 Received: from stargate.chelsio.com ([12.32.117.8]:12294 "EHLO stargate.chelsio.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725772AbgJCDhC (ORCPT ); Fri, 2 Oct 2020 23:37:02 -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 0933akKK003578; Fri, 2 Oct 2020 20:36:47 -0700 Date: Sat, 3 Oct 2020 09:06:46 +0530 From: Krishnamraju Eraparaju To: Sagi Grimberg Cc: Max Gurtovoy , linux-rdma@vger.kernel.org, Potnuri Bharat Teja , Max Gurtovoy Subject: Re: reduce iSERT Max IO size Message-ID: <20201003033644.GA19516@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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4d0b1a3f-2980-c7ed-ef9a-0ed6a9c87a69@grimberg.me> User-Agent: Mutt/1.5.21 (2010-09-15) Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org 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 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?