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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6EAB1C636D6 for ; Thu, 23 Feb 2023 15:35:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234724AbjBWPf3 (ORCPT ); Thu, 23 Feb 2023 10:35:29 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47096 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233711AbjBWPf2 (ORCPT ); Thu, 23 Feb 2023 10:35:28 -0500 Received: from mail-wr1-f48.google.com (mail-wr1-f48.google.com [209.85.221.48]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4947957D3E; Thu, 23 Feb 2023 07:35:27 -0800 (PST) Received: by mail-wr1-f48.google.com with SMTP id r7so10835736wrz.6; Thu, 23 Feb 2023 07:35:27 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=pQe/WnpSMAW2mDbkmE0tjSb/o7wgQczEKKxf9Jtlnnc=; b=xnsIQWehfu2rxxwqtqyhXc9N51RAvVn81fKh7fqu9QQVCLuQQqzFEWOJPGWAZpcwhz RGoYkHXRAJAnhuaPXRL4aejdaXK+MqP75K6tJT7vtJrfEVPrBFHdmuAOZzU+4rVunVvs XdD9xK3YAGVbwB0WDyX0gRhJVnAUywqxTLleafhA5bILXI9egsDEpJcvYn43JLFW50f8 mJywcWzcuh2ki6uRh50ywuGCumVJ65RSYtMXnByThUKMpdvxCUIvI9KbBOsSbSuiGRhr KdL6Gdp7tNH86fXMTUsO+0TcfTcoY9PY8GpUlvHpUS5YMlGZxQazpYBoe2yIgWq+yTlj TP7g== X-Gm-Message-State: AO0yUKVDngE3Ga1oJnVDi57CpYYUR/TS/YIQ6AXZp+piTekvL1dJ71OX EwybbxLF52UCu3tV19uijNJ0AnGsyWo= X-Google-Smtp-Source: AK7set/KFJVUpx9U1606sZfdF40dDGZrrfSPJV+F9VjEhmT/9eemxiLat4EB5PwUkYTjkefYdPluRQ== X-Received: by 2002:a5d:60c7:0:b0:2bf:de9c:4595 with SMTP id x7-20020a5d60c7000000b002bfde9c4595mr9390894wrt.5.1677166525786; Thu, 23 Feb 2023 07:35:25 -0800 (PST) Received: from [10.100.102.14] (85-250-17-149.bb.netvision.net.il. [85.250.17.149]) by smtp.gmail.com with ESMTPSA id v15-20020a5d4a4f000000b002c7107ce17fsm2078608wrs.3.2023.02.23.07.35.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 23 Feb 2023 07:35:25 -0800 (PST) Message-ID: <561afa67-04d0-c675-6bbb-048313da152b@grimberg.me> Date: Thu, 23 Feb 2023 17:35:23 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.7.1 Subject: Re: [LSF/MM/BPF BOF] Userspace command abouts Content-Language: en-US To: Keith Busch Cc: dgilbert@interlog.com, Hannes Reinecke , "linux-nvme@lists.infradead.org" , "linux-block@vger.kernel.org" , "linux-scsi@vger.kernel.org" , lsf-pc@lists.linuxfoundation.org References: <3d3369f1-7ebe-b3b8-804c-ff2b97ec679d@suse.de> <57d8dff9-2fdb-8198-6cdc-7265797a704a@interlog.com> <23526cf9-d912-59a7-4742-6003d6ccfd45@grimberg.me> From: Sagi Grimberg In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org >>>> I did not understand what is the relationship between aborts and CDL. >>>> Sounds to me that this would tie in to something like Time Limited Error >>>> Recovery (TLER) and LR bit set based on ioprio? >>>> >>>> I am unclear where do aborts come into play here. >>> >>> CDL: Command Duration Limits >>> >>> One use case is reading from storage for audio visual output. >>> An application only wants to wait so long (e.g. one or two frames >>> on the video output) before it wants to forget about the current >>> read (i.e. "abort" it) and move onto the next read. An alert viewer >>> might notice a momentary freeze frame. >>> >>> The SCSI CDL mechanism uses the DL0, DL1 and DL2 bits in the READ(16,32) >>> commands. CDL also depends on the CDLP and RWCDLP fields in the >>> REPORT SUPPORTED OPERATION CODES command and one of the CDL >>> mode pages. So there may be some additional "wiring" needed in the >>> SCSI subsystem. >> >> I still don't understand where issuing aborts from userspace come into >> play here... > > The only connection is that aborts are obsolete and unnecessary if > you have a working CDL implementation. OK, that makes sense. Indeed I *think* that nvme can support CDL and if this is useful for userspace then this is an interesting path to take.