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,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 130EBC433E0 for ; Thu, 28 Jan 2021 14:37:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C135364DDF for ; Thu, 28 Jan 2021 14:37:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229596AbhA1Ohk (ORCPT ); Thu, 28 Jan 2021 09:37:40 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44632 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229810AbhA1Ohe (ORCPT ); Thu, 28 Jan 2021 09:37:34 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C9BD7C061573; Thu, 28 Jan 2021 06:36:52 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.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; bh=qfAZf6ZlTjVgH/IQFEPEEQyZ2qBJXEjzt5yHOvBrM7g=; b=v53fKlviZc5sva3sIUfmyQSDwf vECJy6fhl/xvrQxMUjM7yRht/5xeQI133IEUEnazHP2sqyv95gQrAYwKO9ydaaYozNmGs25UNxkdy UZkkqXR5QnaT22xxka1QAHmET9yRHli848etiAdMKtBqo8xxNDmeDyoV/CYSJT34rB7lH38Y9Wp3s r2tt4T0/syQV24vwfbb3Qn5JxqSeHLMa1N9jdwucGbIX+G5CV0MyJ0MebFcTesb784J/y+Kk3t+LX JgnbVLcu5k9nagve01nJ+VY6K2MWWYO3G8UcjXkhp9dHZtDduKjMCQvLq74iEOSELcAEUa6c9gUgk +cePZcCA==; Received: from hch by casper.infradead.org with local (Exim 4.94 #2 (Red Hat Linux)) id 1l58PY-008Zc6-Qb; Thu, 28 Jan 2021 14:36:41 +0000 Date: Thu, 28 Jan 2021 14:36:40 +0000 From: Christoph Hellwig To: JeffleXu Cc: Christoph Hellwig , snitzer@redhat.com, joseph.qi@linux.alibaba.com, dm-devel@redhat.com, linux-block@vger.kernel.org, io-uring@vger.kernel.org Subject: Re: [PATCH v2 3/6] block: add iopoll method to support bio-based IO polling Message-ID: <20210128143640.GA2043450@infradead.org> References: <20210125121340.70459-1-jefflexu@linux.alibaba.com> <20210125121340.70459-4-jefflexu@linux.alibaba.com> <20210128084016.GA1951639@infradead.org> <7d5402f2-c4d7-9d9a-e637-54a2dd349b3f@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7d5402f2-c4d7-9d9a-e637-54a2dd349b3f@linux.alibaba.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On Thu, Jan 28, 2021 at 07:52:05PM +0800, JeffleXu wrote: > > > On 1/28/21 4:40 PM, Christoph Hellwig wrote: > > On Mon, Jan 25, 2021 at 08:13:37PM +0800, Jeffle Xu wrote: > >> +int blk_poll(struct request_queue *q, blk_qc_t cookie, bool spin) > > > > Can you split the guts of this function into two separate helpers > > for the mq vs non-mq case? As is is is a little hard to read and > > introduced extra branches in the fast path. > > > > I know your consideration, actually I had ever tried. > > I can extract some helper functions, but I'm doubted if the extra > function call is acceptable. > > Besides, the iteration logic is generic and I'm afraid the branch or > function call is unavoidable. Or if we maintain two separate function > for mq and dm, the code duplication may be unavoidable. I'd just split the functions entirely at the highest level.