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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 00CBFC7618F for ; Mon, 15 Jul 2019 11:22:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C87DE2081C for ; Mon, 15 Jul 2019 11:22:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="PHsHodDx" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729821AbfGOLWB (ORCPT ); Mon, 15 Jul 2019 07:22:01 -0400 Received: from mail-lj1-f195.google.com ([209.85.208.195]:36421 "EHLO mail-lj1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729725AbfGOLWA (ORCPT ); Mon, 15 Jul 2019 07:22:00 -0400 Received: by mail-lj1-f195.google.com with SMTP id i21so15777034ljj.3; Mon, 15 Jul 2019 04:21:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=gVFqb2ZAh43FCjbdEnlEQIc2JRQwHvSxVmi0yjJ0kAo=; b=PHsHodDxb4KtiLFGCXDUFeRaswzWlgBJeoV92SFmmlP3kyYv0P1xtwA+t/SRQ5jI4a aW4oAyM6WRHI3loIlxsPfdJdrnQP7lKwhECbIHlr8iT7eXp1ihyOU/9NDkaEQcJsEpUx NgHVebj8noMJBQ2BXFmxc9cJnA8/CZP5ye3me20P1QaJxJM5WvA85/rFBzPh3M/acgqm 80jtwgXUm/hCZp8m/OyoXm+bLI0cHTNv+EtVBWoCAU7we9A0y901KhnQvH672gJM4QTL mEIQtOOXxAUzMSRlAAQGsxzVgMWtc4kdnyAiwi6GnlDUjhxtpTa/XNV/+YqANlLmgbS5 /n1w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=gVFqb2ZAh43FCjbdEnlEQIc2JRQwHvSxVmi0yjJ0kAo=; b=fUziWqeV8w+gQRAWXoB4uq0iQM83bc5XTI7YwYBqOTSJLgoyUwLsCM9bYOdIMOi97B h4GP/mEdr4dDT0qMWMPoqSXbN7CM3CqsL/Xf+D1UfhtMW/FBZQEEskK2+XKcoBNSRKKB O/QEf+ciCJ0l+DybpgaiRqnm+Zm4vO+ohFGKwXRkNE1o/VLPs4sU1Y0omqY3TvFNuAH7 0aaTt2PZPhDnEXm0ZUqfjaMOeU3+lJk4GZsICP+yIrBwvNOCRoyvwM5CHyDlEQV7bzvJ 5Lyw2FzBO85X5jsSxFyMOCYbhUk3ma8MMR7tJcySkPC7E74ncMeh7ytqIhuI7go0rOp4 UvfQ== X-Gm-Message-State: APjAAAWL+sEsHQUPvODlYNx1v8dVBXs0bfwaFJPg2cIWplZ28P8BRuV6 6UXTtoCzH7zTeoPRcjgu4BTmQF/3DwdAO6+Wkh8= X-Google-Smtp-Source: APXvYqz29uFTNm018kjJZXVHplrRKz3F5/gtgS4MImXtgnN/jM6PuvZjPvdIIlU8BM5o+sM2V1Yxzrx0N9s6knwKoEs= X-Received: by 2002:a2e:3e01:: with SMTP id l1mr10882783lja.208.1563189718743; Mon, 15 Jul 2019 04:21:58 -0700 (PDT) MIME-Version: 1.0 References: <20190620150337.7847-1-jinpuwang@gmail.com> <11653912-924a-965a-45fe-3abd1ca00053@grimberg.me> In-Reply-To: <11653912-924a-965a-45fe-3abd1ca00053@grimberg.me> From: Jinpu Wang Date: Mon, 15 Jul 2019 13:21:47 +0200 Message-ID: Subject: Re: [PATCH v4 00/25] InfiniBand Transport (IBTRS) and Network Block Device (IBNBD) To: Sagi Grimberg Cc: Danil Kipnis , linux-block@vger.kernel.org, linux-rdma@vger.kernel.org, Jens Axboe , Christoph Hellwig , bvanassche@acm.org, jgg@mellanox.com, dledford@redhat.com, Roman Pen , Greg Kroah-Hartman Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Sagi Grimberg =E4=BA=8E2019=E5=B9=B47=E6=9C=8812=E6=97= =A5=E5=91=A8=E4=BA=94 =E4=B8=8B=E5=8D=889:40=E5=86=99=E9=81=93=EF=BC=9A > > > > Hi Sagi, > > > >>>> Another question, from what I understand from the code, the client > >>>> always rdma_writes data on writes (with imm) from a remote pool of > >>>> server buffers dedicated to it. Essentially all writes are immediate= (no > >>>> rdma reads ever). How is that different than using send wrs to a set= of > >>>> pre-posted recv buffers (like all others are doing)? Is it faster? > >>> At the very beginning of the project we did some measurements and saw= , > >>> that it is faster. I'm not sure if this is still true > >> > >> Its not significantly faster (can't imagine why it would be). > >> What could make a difference is probably the fact that you never > >> do rdma reads for I/O writes which might be better. Also perhaps the > >> fact that you normally don't wait for send completions before completi= ng > >> I/O (which is broken), and the fact that you batch recv operations. > > > > I don't know how do you come to the conclusion we don't wait for send > > completion before completing IO. > > > > We do chain wr on successfull read request from server, see funtion > > rdma_write_sg, > > I was referring to the client side Hi Sagi, I checked the 3 commits you mentioned in earlier thread again, I now get your point. You meant the behavior following commits try to fix. 4af7f7ff92a4 ("nvme-rdma: don't complete requests before a send work request has completed") b4b591c87f2b ("nvme-rdma: don't suppress send completions") In this sense, ibtrs client side are not waiting for the completions for RDMA WRITE WR to finish. But we did it right for local invalidation. I checked SRP/iser, they are not even wait for local invalidation, no signal flag set. If it's a problem, we should fix them too, maybe more. My question is do you see the behavior (HCA retry send due to drop ack ) in the field, is it possible to reproduce? Thanks, Jack