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 286BAC77B75 for ; Thu, 18 May 2023 01:23:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229453AbjERBXt (ORCPT ); Wed, 17 May 2023 21:23:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33690 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229452AbjERBXt (ORCPT ); Wed, 17 May 2023 21:23:49 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 05785421F for ; Wed, 17 May 2023 18:23:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1684372983; 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=dDkHBjGl9sCc9Caa6fvEp3TJEYPKjYbAbq2RguBbjUc=; b=cVw/hXlff0q1DNNIzIyewZ1TWX69RtNPJp+jzPgIYzdT0n1JnyDY6JcZdcm7QOeU/ML+cG GqMu8NPquJ4k1Cx+rxUUa/D+ANveIEUZfwgyKmyg2fkP0GoyBTqmW280eS/beZOTAsXSws SHzLIsQCkNYeOzX2ETUjFT/5ejz/ogI= 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-317-q0phaVb9O222CjUdi_Ti-w-1; Wed, 17 May 2023 21:22:59 -0400 X-MC-Unique: q0phaVb9O222CjUdi_Ti-w-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 DA80387DC00; Thu, 18 May 2023 01:22:58 +0000 (UTC) Received: from ovpn-8-16.pek2.redhat.com (ovpn-8-25.pek2.redhat.com [10.72.8.25]) by smtp.corp.redhat.com (Postfix) with ESMTPS id F386463F5B; Thu, 18 May 2023 01:22:54 +0000 (UTC) Date: Thu, 18 May 2023 09:22:49 +0800 From: Ming Lei To: Keith Busch Cc: Bart Van Assche , Jens Axboe , linux-block@vger.kernel.org, Christoph Hellwig , Kanchan Joshi Subject: Re: [PATCH V2 2/2] blk-mq: make sure elevator callbacks aren't called for passthrough request Message-ID: References: <20230515144601.52811-1-ming.lei@redhat.com> <20230515144601.52811-3-ming.lei@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 3.1 on 10.11.54.5 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Wed, May 17, 2023 at 12:13:04PM -0600, Keith Busch wrote: > On Wed, May 17, 2023 at 11:26:32AM +0800, Ming Lei wrote: > > On Tue, May 16, 2023 at 08:47:46AM -0600, Keith Busch wrote: > > > > > And the passthrough case is special with users of that interface taking > > > on a greater responsibility and generally want the kernel out of the > > > way. I don't think anyone would purposefully run a tag intense workload > > > through that engine at the same time as using a generic one with the > > > scheduler. It definitely should still work, but it doesn't need to be > > > fair, right? > > > > I guess it may work, but question is that what we can get from this kind > > of big change? And I think this approach may be one following work if it is > > proved as useful. > > I'm just trying to remove any need for side channels to bypass block > layer functionality, like this one: > > http://lists.infradead.org/pipermail/linux-nvme/2023-April/039522.html > In "io_uring attached nvme queue" patchset, Kanchan tried to bypass request/bio completely, and same with blk-mq's pt code path. You mean you'd suggest to still reuse req/bio & blk-mq pt code path for "io_uring attached nvme queue"? Cc Kanchan. Thanks, Ming