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=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, 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 072B7C33C9E for ; Sat, 1 Feb 2020 08:20:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BF6E22067C for ; Sat, 1 Feb 2020 08:20:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="oIO7D1Dm" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726197AbgBAIUm (ORCPT ); Sat, 1 Feb 2020 03:20:42 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:38840 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726133AbgBAIUl (ORCPT ); Sat, 1 Feb 2020 03:20:41 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=gE9Mx3W9x+ojBglaKL+EtPiMsFFLFj22q4iMOnSc8TM=; b=oIO7D1DmZpP8/qRY7jm6xdQb/ VPeEbhJkRP+/M27gI9gnFQ4p0zh/L4svRplLCAP9x9cTrhoIYGduRUHT9zjbk/ctMo1UXdcVlOpJv VYUbUYCj2/6yb0SZRHVPPbKsZjGDrR6HFB+a2Z8WALrd2uSfONMCycox4paInD6sMEqHJeHzeCE7Y QDX+YZJcEqkN3aDPVisx4RBep9af/vcUWuVonYXwAektJibZf8QhaEy8AAPBvzdE4LUn8S5KPz7ZZ /rPw7im7gZbz3tnqpp/BajGRsha5NSf0MR22+vh9iHsdKI1EKl/ydsHtpS/CdGLobDOs474H6ZSzg YnKzjERYw==; Received: from hch by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1ixo14-0003cQ-1S; Sat, 01 Feb 2020 08:20:34 +0000 Date: Sat, 1 Feb 2020 00:20:34 -0800 From: Christoph Hellwig To: Andrzej Jakowski Cc: Christoph Hellwig , axboe@kernel.dk, song@kernel.org, linux-block@vger.kernel.org, linux-raid@vger.kernel.org, Artur Paszkiewicz Subject: Re: [PATCH 1/2] block: introduce polling on bio level Message-ID: <20200201082034.GA8423@infradead.org> References: <20200126044138.5066-1-andrzej.jakowski@linux.intel.com> <20200126044138.5066-2-andrzej.jakowski@linux.intel.com> <20200131063407.GB6267@infradead.org> <081badca-ab0f-f666-1e5e-71992f93a157@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <081badca-ab0f-f666-1e5e-71992f93a157@linux.intel.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Fri, Jan 31, 2020 at 11:51:43AM -0700, Andrzej Jakowski wrote: > On 1/30/20 11:34 PM, Christoph Hellwig wrote: > > Can you explain this check? This looks weird to me I think we need > > a generalized check if a make_request based driver supports REQ_NOWAIT > > instead (and as a separate patch / patchset). > > Original check used to reject polled IO for stackable block devices as "not > supported". To solve that situation I introduced additional check to reject > all non REQ_HIPRI requests. That check is not intended to generalize, like > you indicated, but to conservatively select which requests to accept. > Perhaps there is better way to do that. Any suggestions? REQ_NOWAIT and REQ_HIPRI are completley unrelated concepts and they need to be dealt with entirely separately.