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 3B98ACA90AF for ; Wed, 13 May 2020 12:27:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1885A23126 for ; Wed, 13 May 2020 12:27:55 +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="Mv+LTLDu" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729688AbgEMM1y (ORCPT ); Wed, 13 May 2020 08:27:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45650 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726020AbgEMM1y (ORCPT ); Wed, 13 May 2020 08:27:54 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0AA51C061A0C for ; Wed, 13 May 2020 05:27:54 -0700 (PDT) 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; bh=KshPX4OSLDyhYg2bK/7AYzTciP1pjieRzRjIQ+fRtWI=; b=Mv+LTLDuwXYRDvIhSmF9/bJM8m x3mp8q0mI0FEkm2a7n0f8yQzBNTWZScFo8WKyGMmI1BlsfBT36cbjQ2sZ+2BB7LNcK8kkdhcdW+xQ nDGTsQURNN+b7faqbaOywEfJJcTAUDG1NBmyusdjR5gKmrjarzf9FCbnVWjvT2K2HKkj4DpUBjJOq 11K0KxEZGvBFYyRg+YhyTa80pH+EQaJrUmgcJ9yZlIHUrEg+APH33ui2bZ7QEFlsSgXHSzwmEJuIa N0cV4Q4ZWEFaZB3Vm0TWCzVulPicy2J00GyDxCSwRyRMoVOW/RrsVhM7nWTi3gaUvFMPZMMUt6x7h 1G4JulzQ==; Received: from hch by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1jYqUL-000666-68; Wed, 13 May 2020 12:27:53 +0000 Date: Wed, 13 May 2020 05:27:53 -0700 From: Christoph Hellwig To: Ming Lei Cc: Jens Axboe , linux-block@vger.kernel.org, Sagi Grimberg , Baolin Wang , Christoph Hellwig Subject: Re: [PATCH 3/9] blk-mq: don't predicate last flag in blk_mq_dispatch_rq_list Message-ID: <20200513122753.GC23958@infradead.org> References: <20200513095443.2038859-1-ming.lei@redhat.com> <20200513095443.2038859-4-ming.lei@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200513095443.2038859-4-ming.lei@redhat.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 Wed, May 13, 2020 at 05:54:37PM +0800, Ming Lei wrote: > .commit_rqs() is supposed to handle partial dispatch when driver may not > see .last of flag passed to .queue_rq(). > > We have added .commit_rqs() in case of partial dispatch and all consumers > of bd->last have implemented .commit_rqs() callback, so it is perfect to > pass real .last flag of the request list to .queue_rq() instead of faking > it by trying to allocate driver tag for next request in the batching list. The current case still seems like a nice optimization to avoid an extra indirect function call. So if you want to get rid of it I think it at least needs a better rationale.