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 B9534C433E7 for ; Thu, 8 Oct 2020 19:14:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 56D77221FE for ; Thu, 8 Oct 2020 19:14:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726792AbgJHTOs (ORCPT ); Thu, 8 Oct 2020 15:14:48 -0400 Received: from stargate.chelsio.com ([12.32.117.8]:36257 "EHLO stargate.chelsio.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726469AbgJHTOs (ORCPT ); Thu, 8 Oct 2020 15:14:48 -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 098Ix6eR027138; Thu, 8 Oct 2020 11:59:08 -0700 Date: Fri, 9 Oct 2020 00:29:06 +0530 From: Krishnamraju Eraparaju To: Bernard Metzler Cc: Max Gurtovoy , Sagi Grimberg , linux-rdma@vger.kernel.org, Potnuri Bharat Teja , Max Gurtovoy Subject: Re: Re: reduce iSERT Max IO size Message-ID: <20201008185905.GA21229@chelsio.com> References: <20201007033619.GA11425@chelsio.com> <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: User-Agent: Mutt/1.5.21 (2010-09-15) Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On Thursday, October 10/08/20, 2020 at 13:12:39 +0000, Bernard Metzler wrote: > -----"Krishnamraju Eraparaju" wrote: ----- > > >To: "Max Gurtovoy" > >From: "Krishnamraju Eraparaju" > >Date: 10/07/2020 05:36AM > >Cc: "Sagi Grimberg" , linux-rdma@vger.kernel.org, > >"Potnuri Bharat Teja" , "Max Gurtovoy" > > > >Subject: [EXTERNAL] Re: reduce iSERT Max IO size > > > >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 siw, this limit is not determined by resource constraints. > We could bump it up to 512, or higher. What is a reasonable > maximum, from iSER view? If the most common IO sizes are 4K & 8K, then the reasonable max IO size of 256 pages(1 MiB) would be appropriate, by default. currently, NVMet-rdma also limits max IO size to 1MiB. > > > >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? > > >