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 8E8A6C433F5 for ; Wed, 23 Mar 2022 01:27:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231839AbiCWB3O (ORCPT ); Tue, 22 Mar 2022 21:29:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47190 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230118AbiCWB3N (ORCPT ); Tue, 22 Mar 2022 21:29:13 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 319666FA0A for ; Tue, 22 Mar 2022 18:27:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1647998864; 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=uv0x7IhJh6HUYVs80OeWrM0ewUxdezb68rDatc83fOk=; b=i0e3AHpYRSgtgafQY6Z5vnaCbhGPdGai2K7IHFn5z/DqKgeK3IVH0V8ri/gTflSoOrLYUX eSmJf4qcbpN05zqOmu4S4NJnHjh0/OMByrdZsfZyasy90TCIsmWyQ/9fFFqum0r7aFU6hE aVBhq2olBu0l5SeSO5u5teTt3zSWGpY= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-508-pGai4B4ePTaoBfBKVAlgbw-1; Tue, 22 Mar 2022 21:27:40 -0400 X-MC-Unique: pGai4B4ePTaoBfBKVAlgbw-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 0E99C85A5BE; Wed, 23 Mar 2022 01:27:40 +0000 (UTC) Received: from T590 (ovpn-8-19.pek2.redhat.com [10.72.8.19]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E12497AD1; Wed, 23 Mar 2022 01:27:22 +0000 (UTC) Date: Wed, 23 Mar 2022 09:27:16 +0800 From: Ming Lei To: Kanchan Joshi Cc: Kanchan Joshi , Christoph Hellwig , Jens Axboe , Keith Busch , Pavel Begunkov , io-uring@vger.kernel.org, linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, sbates@raithlin.com, logang@deltatee.com, Pankaj Raghav , Javier =?iso-8859-1?Q?Gonz=E1lez?= , Luis Chamberlain , Adam Manzanares , Anuj Gupta Subject: Re: [PATCH 10/17] block: wire-up support for plugging Message-ID: References: <20220308152105.309618-1-joshi.k@samsung.com> <20220308152105.309618-11-joshi.k@samsung.com> <20220310083400.GD26614@lst.de> <20220321070208.GA5107@test-zns> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220321070208.GA5107@test-zns> X-Scanned-By: MIMEDefang 2.79 on 10.11.54.5 Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On Mon, Mar 21, 2022 at 12:32:08PM +0530, Kanchan Joshi wrote: > On Mon, Mar 14, 2022 at 10:40:53PM +0800, Ming Lei wrote: > > On Thu, Mar 10, 2022 at 06:10:08PM +0530, Kanchan Joshi wrote: > > > On Thu, Mar 10, 2022 at 2:04 PM Christoph Hellwig wrote: > > > > > > > > On Tue, Mar 08, 2022 at 08:50:58PM +0530, Kanchan Joshi wrote: > > > > > From: Jens Axboe > > > > > > > > > > Add support to use plugging if it is enabled, else use default path. > > > > > > > > The subject and this comment don't really explain what is done, and > > > > also don't mention at all why it is done. > > > > > > Missed out, will fix up. But plugging gave a very good hike to IOPS. > > > > But how does plugging improve IOPS here for passthrough request? Not > > see plug->nr_ios is wired to data.nr_tags in blk_mq_alloc_request(), > > which is called by nvme_submit_user_cmd(). > > Yes, one tag at a time for each request, but none of the request gets > dispatched and instead added to the plug. And when io_uring ends the > plug, the whole batch gets dispatched via ->queue_rqs (otherwise it used > to be via ->queue_rq, one request at a time). > > Only .plug impact looks like this on passthru-randread: > > KIOPS(depth_batch) 1_1 8_2 64_16 128_32 > Without plug 159 496 784 785 > With plug 159 525 991 1044 > > Hope it does clarify. OK, thanks for your confirmation, then the improvement should be from batch submission only. If cached request is enabled, I guess the number could be better. Thanks, Ming