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[68.160.176.52]) by smtp.gmail.com with ESMTPSA id o21sm5295158qta.89.2022.01.10.11.26.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 10 Jan 2022 11:26:30 -0800 (PST) Date: Mon, 10 Jan 2022 14:26:29 -0500 From: Mike Snitzer To: Ming Lei Message-ID: References: <20211221141459.1368176-1-ming.lei@redhat.com> MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.85 on 10.11.54.9 X-loop: dm-devel@redhat.com Cc: Christoph Hellwig , Jens Axboe , dm-devel@redhat.com, linux-block@vger.kernel.org Subject: Re: [dm-devel] [PATCH 0/3] blk-mq/dm-rq: support BLK_MQ_F_BLOCKING for dm-rq X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dm-devel-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Tue, Dec 28 2021 at 4:30P -0500, Mike Snitzer wrote: > On Wed, Dec 22 2021 at 11:16P -0500, > Ming Lei wrote: > > > On Tue, Dec 21, 2021 at 08:21:39AM -0800, Christoph Hellwig wrote: > > > On Tue, Dec 21, 2021 at 10:14:56PM +0800, Ming Lei wrote: > > > > Hello, > > > > > > > > dm-rq may be built on blk-mq device which marks BLK_MQ_F_BLOCKING, so > > > > dm_mq_queue_rq() may become to sleep current context. > > > > > > > > Fixes the issue by allowing dm-rq to set BLK_MQ_F_BLOCKING in case that > > > > any underlying queue is marked as BLK_MQ_F_BLOCKING. > > > > > > > > DM request queue is allocated before allocating tagset, this way is a > > > > bit special, so we need to pre-allocate srcu payload, then use the queue > > > > flag of QUEUE_FLAG_BLOCKING for locking dispatch. > > > > > > What is the benefit over just forcing bio-based dm-mpath for these > > > devices? > > > > At least IO scheduler can't be used for bio based dm-mpath, also there should > > be other drawbacks for bio based mpath and request mpath is often the default > > option, maybe Mike has more input about bio vs request dm-mpath. > > Yeah, people use request-based for IO scheduling and more capable path > selectors. Imposing bio-based would be a pretty jarring workaround for > BLK_MQ_F_BLOCKING. request-based DM should properly support it. > > I'm on vacation for the next week but will have a look at this > patchset once I'm back. I replied last week and hoped Jens would pick this patchset up after my Reviewed-by of patch 3/3. Christoph wasn't back though, so best to kick this thread again. Thoughts on this patchset? Thanks, Mike -- dm-devel mailing list dm-devel@redhat.com https://listman.redhat.com/mailman/listinfo/dm-devel 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 46298C433F5 for ; Mon, 10 Jan 2022 19:26:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243186AbiAJT0g (ORCPT ); Mon, 10 Jan 2022 14:26:36 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:35023 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243038AbiAJT0e (ORCPT ); Mon, 10 Jan 2022 14:26:34 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1641842793; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=yZ08XZ8idEJY7dNL/CjmIYmeW6lP9L5GGjs6T10cj9s=; b=K9ExXwrZtIhLRb0PGg4uVChsHUwconXfBhnWKXmkMvIioFg66Dch2VVv772u47a+g75rmt oYEIEAmEPPIZHeNx4BMNnN9m7EOnLq16E7hvjAV8/HtLPtNzuQqW9Sgm1/79wlRx7OWd5U b6hmSM1vn0xQvzVba4jYyXAc7c3pEbk= Received: from mail-qt1-f200.google.com (mail-qt1-f200.google.com [209.85.160.200]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-116-Ygy16UhGPwaMYrs51C8O9Q-1; Mon, 10 Jan 2022 14:26:32 -0500 X-MC-Unique: Ygy16UhGPwaMYrs51C8O9Q-1 Received: by mail-qt1-f200.google.com with SMTP id cp8-20020a05622a420800b002c617119aafso2509516qtb.4 for ; Mon, 10 Jan 2022 11:26:32 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=yZ08XZ8idEJY7dNL/CjmIYmeW6lP9L5GGjs6T10cj9s=; b=tE817WvQmp7enG6EhsaSadCRGfd03cxGgRV3d4jQa3NRZtseoMy/GMNisOypFp7jHD tr+KQEJKzP/RHjBnGPm3go/czr9FSnU+v6JEgP9+Z6UixMoN87YPvN1h3x4GVrvDYTd6 AqNMBDc8j63lXRBfDstmbaUG2GbqnM6dHYBgRgnH4+bC33zBGCI+6pkCztNQ1rDvCXR8 Dbws5Y/WGJOBC7l/KPHYWd6gzC+z4pWyI5ozw0jFnf03Ps+ck6jfhPUyXLbJYzFupF+e tcTz3G3qicCwyBFkK2L4uHm/fV726Plpy9g8T9xi8UbdNlqDa9cOOoZzoYsXlSdtjhjg hiQA== X-Gm-Message-State: AOAM532qR9073Hdw4n8nBitat1i0sZ+rGIXC32b7yXfQ/KlZvWkITXrx W2H8lWQVxThK5bd4e5ao/fMQm8Z0ACg8Muam4P1fGR4xd9jRr+hAvjHT32fneJIKlLdKp2GEZ9G 1R0CWHj/qNZsUX4WI2GZ1Qw== X-Received: by 2002:a05:620a:2015:: with SMTP id c21mr883060qka.383.1641842791595; Mon, 10 Jan 2022 11:26:31 -0800 (PST) X-Google-Smtp-Source: ABdhPJwwHjM+t1bgDCUU60h+0opXhwpp98ZNY2fG6MTGB7kRs/0equHHPiJppDI0OZXqDMqD3jRW+w== X-Received: by 2002:a05:620a:2015:: with SMTP id c21mr883046qka.383.1641842791400; Mon, 10 Jan 2022 11:26:31 -0800 (PST) Received: from localhost (pool-68-160-176-52.bstnma.fios.verizon.net. [68.160.176.52]) by smtp.gmail.com with ESMTPSA id o21sm5295158qta.89.2022.01.10.11.26.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 10 Jan 2022 11:26:30 -0800 (PST) Date: Mon, 10 Jan 2022 14:26:29 -0500 From: Mike Snitzer To: Ming Lei Cc: Christoph Hellwig , Jens Axboe , linux-block@vger.kernel.org, dm-devel@redhat.com Subject: Re: [PATCH 0/3] blk-mq/dm-rq: support BLK_MQ_F_BLOCKING for dm-rq Message-ID: References: <20211221141459.1368176-1-ming.lei@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Tue, Dec 28 2021 at 4:30P -0500, Mike Snitzer wrote: > On Wed, Dec 22 2021 at 11:16P -0500, > Ming Lei wrote: > > > On Tue, Dec 21, 2021 at 08:21:39AM -0800, Christoph Hellwig wrote: > > > On Tue, Dec 21, 2021 at 10:14:56PM +0800, Ming Lei wrote: > > > > Hello, > > > > > > > > dm-rq may be built on blk-mq device which marks BLK_MQ_F_BLOCKING, so > > > > dm_mq_queue_rq() may become to sleep current context. > > > > > > > > Fixes the issue by allowing dm-rq to set BLK_MQ_F_BLOCKING in case that > > > > any underlying queue is marked as BLK_MQ_F_BLOCKING. > > > > > > > > DM request queue is allocated before allocating tagset, this way is a > > > > bit special, so we need to pre-allocate srcu payload, then use the queue > > > > flag of QUEUE_FLAG_BLOCKING for locking dispatch. > > > > > > What is the benefit over just forcing bio-based dm-mpath for these > > > devices? > > > > At least IO scheduler can't be used for bio based dm-mpath, also there should > > be other drawbacks for bio based mpath and request mpath is often the default > > option, maybe Mike has more input about bio vs request dm-mpath. > > Yeah, people use request-based for IO scheduling and more capable path > selectors. Imposing bio-based would be a pretty jarring workaround for > BLK_MQ_F_BLOCKING. request-based DM should properly support it. > > I'm on vacation for the next week but will have a look at this > patchset once I'm back. I replied last week and hoped Jens would pick this patchset up after my Reviewed-by of patch 3/3. Christoph wasn't back though, so best to kick this thread again. Thoughts on this patchset? Thanks, Mike