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=-5.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 195C6C433B4 for ; Fri, 16 Apr 2021 09:07:30 +0000 (UTC) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id A3D386100C for ; Fri, 16 Apr 2021 09:07:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A3D386100C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=tempfail smtp.mailfrom=dm-devel-bounces@redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1618564048; h=from:from:sender:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:list-id:list-help: list-unsubscribe:list-subscribe:list-post; bh=madAG/glkPZpprH3pVhF4bYY/INueN3/xHIcfI8U5oo=; b=KXRdSFeAQQd6o6W39lrlRyfyMQdxb3PVLOJBvFzkrPbheYcNwWwsmnpWc1KYswdqtdtYfr m/xbubwnNNgYzEkMv8z9t2gZcNwUgbLOUglWpzky9GV1iMVQiv/Dc34HiUKYf0Akc1sMGa smIxA7B+WfnLBfc4ltqTSujagQNDD9o= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-307-sLr4Z4WeOZWPJ2rwKmu59Q-1; Fri, 16 Apr 2021 05:07:26 -0400 X-MC-Unique: sLr4Z4WeOZWPJ2rwKmu59Q-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id D38646D249; Fri, 16 Apr 2021 09:07:20 +0000 (UTC) Received: from colo-mx.corp.redhat.com (colo-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.21]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 81AE75D9C0; Fri, 16 Apr 2021 09:07:20 +0000 (UTC) Received: from lists01.pubmisc.prod.ext.phx2.redhat.com (lists01.pubmisc.prod.ext.phx2.redhat.com [10.5.19.33]) by colo-mx.corp.redhat.com (Postfix) with ESMTP id 7AE1B44A5E; Fri, 16 Apr 2021 09:07:19 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) by lists01.pubmisc.prod.ext.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id 13G97Isl002163 for ; Fri, 16 Apr 2021 05:07:18 -0400 Received: by smtp.corp.redhat.com (Postfix) id C5CB55D9DE; Fri, 16 Apr 2021 09:07:18 +0000 (UTC) Received: from T590 (ovpn-12-36.pek2.redhat.com [10.72.12.36]) by smtp.corp.redhat.com (Postfix) with ESMTPS id ABCBA5D9C0; Fri, 16 Apr 2021 09:07:06 +0000 (UTC) Date: Fri, 16 Apr 2021 17:07:01 +0800 From: Ming Lei To: Jeffle Xu Message-ID: References: <20210401021927.343727-12-ming.lei@redhat.com> <20210416080037.26335-1-jefflexu@linux.alibaba.com> MIME-Version: 1.0 In-Reply-To: <20210416080037.26335-1-jefflexu@linux.alibaba.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-loop: dm-devel@redhat.com Cc: axboe@kernel.dk, linux-block@vger.kernel.org, dm-devel@redhat.com, snitzer@redhat.com Subject: Re: [dm-devel] [PATCH] block: introduce QUEUE_FLAG_POLL_CAP flag 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 2.79 on 10.5.11.14 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 Fri, Apr 16, 2021 at 04:00:37PM +0800, Jeffle Xu wrote: > Hi, > How about this patch to remove the extra poll_capable() method? > > And the following 'dm: support IO polling for bio-based dm device' needs > following change. > > ``` > + /* > + * Check for request-based device is remained to > + * dm_mq_init_request_queue()->blk_mq_init_allocated_queue(). > + * For bio-based device, only set QUEUE_FLAG_POLL when all underlying > + * devices supporting polling. > + */ > + if (__table_type_bio_based(t->type)) { > + if (dm_table_supports_poll(t)) { > + blk_queue_flag_set(QUEUE_FLAG_POLL_CAP, q); > + blk_queue_flag_set(QUEUE_FLAG_POLL, q); > + } > + else { > + blk_queue_flag_clear(QUEUE_FLAG_POLL, q); > + blk_queue_flag_clear(QUEUE_FLAG_POLL_CAP, q); > + } > + } > ``` Frankly speaking, I don't see any value of using QUEUE_FLAG_POLL_CAP for DM, and the result is basically subset of treating DM as always being capable of polling. Also underlying queue change(either limits or flag) won't be propagated to DM/MD automatically. Strictly speaking it doesn't matter if all underlying queues are capable of supporting polling at the exact time of 'write sysfs/poll', cause any of them may change in future. So why not start with the simplest approach(always capable of polling) which does meet normal bio based polling requirement? Thanks, Ming -- 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 X-Spam-Level: X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 B3C19C433B4 for ; Fri, 16 Apr 2021 09:07:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8BF586115B for ; Fri, 16 Apr 2021 09:07:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238478AbhDPJHq (ORCPT ); Fri, 16 Apr 2021 05:07:46 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:27924 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235236AbhDPJHq (ORCPT ); Fri, 16 Apr 2021 05:07:46 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1618564041; 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=+wMsZ8Ea8gNm8RDgnIP3hOgRT7j4TBX+oKP32cZ43c0=; b=EGKRAJnQc2DRN4Czw6IZj8qoatn4x8fa8Xa7JncxgWD0u72zklRWcQQ+FvLJXrhgX33oiZ bNBnSt4I3jHYMT6lGjph5IMONz69ZIffaYmTM0v5ARAxRbDOngDWb2eDY4Yvr0M7XLaBH/ ZHaeZpKuK+6Fc7QwAm4ZVftqXn3CyaA= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-35-9TNrUrp4Maa7T95z6bRG0Q-1; Fri, 16 Apr 2021 05:07:19 -0400 X-MC-Unique: 9TNrUrp4Maa7T95z6bRG0Q-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id B662487A826; Fri, 16 Apr 2021 09:07:18 +0000 (UTC) Received: from T590 (ovpn-12-36.pek2.redhat.com [10.72.12.36]) by smtp.corp.redhat.com (Postfix) with ESMTPS id ABCBA5D9C0; Fri, 16 Apr 2021 09:07:06 +0000 (UTC) Date: Fri, 16 Apr 2021 17:07:01 +0800 From: Ming Lei To: Jeffle Xu Cc: snitzer@redhat.com, axboe@kernel.dk, linux-block@vger.kernel.org, dm-devel@redhat.com Subject: Re: [PATCH] block: introduce QUEUE_FLAG_POLL_CAP flag Message-ID: References: <20210401021927.343727-12-ming.lei@redhat.com> <20210416080037.26335-1-jefflexu@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210416080037.26335-1-jefflexu@linux.alibaba.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Fri, Apr 16, 2021 at 04:00:37PM +0800, Jeffle Xu wrote: > Hi, > How about this patch to remove the extra poll_capable() method? > > And the following 'dm: support IO polling for bio-based dm device' needs > following change. > > ``` > + /* > + * Check for request-based device is remained to > + * dm_mq_init_request_queue()->blk_mq_init_allocated_queue(). > + * For bio-based device, only set QUEUE_FLAG_POLL when all underlying > + * devices supporting polling. > + */ > + if (__table_type_bio_based(t->type)) { > + if (dm_table_supports_poll(t)) { > + blk_queue_flag_set(QUEUE_FLAG_POLL_CAP, q); > + blk_queue_flag_set(QUEUE_FLAG_POLL, q); > + } > + else { > + blk_queue_flag_clear(QUEUE_FLAG_POLL, q); > + blk_queue_flag_clear(QUEUE_FLAG_POLL_CAP, q); > + } > + } > ``` Frankly speaking, I don't see any value of using QUEUE_FLAG_POLL_CAP for DM, and the result is basically subset of treating DM as always being capable of polling. Also underlying queue change(either limits or flag) won't be propagated to DM/MD automatically. Strictly speaking it doesn't matter if all underlying queues are capable of supporting polling at the exact time of 'write sysfs/poll', cause any of them may change in future. So why not start with the simplest approach(always capable of polling) which does meet normal bio based polling requirement? Thanks, Ming