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=-2.8 required=3.0 tests=BAYES_00,DATE_IN_PAST_12_24, 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 57E71C4363A for ; Wed, 28 Oct 2020 22:12:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D77A024724 for ; Wed, 28 Oct 2020 22:11:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="MEr4Wj2p" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730774AbgJ1WL4 (ORCPT ); Wed, 28 Oct 2020 18:11:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52518 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730738AbgJ1WLy (ORCPT ); Wed, 28 Oct 2020 18:11:54 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1C7A6C0613CF for ; Wed, 28 Oct 2020 15:11:54 -0700 (PDT) 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=11r151o8JcIiklZdrY5InpTby+OlWFUHOfysaQ6dEeo=; b=MEr4Wj2p6V6PCicC2/5IqSL14D CvUuk7+ZmDja8bW9YCBqbzS8GUFijYKiYAa8vT88s7Kjl3vvBnadljzN5Rz40L7uUZrkrzbdF8Ygi EyGe1dGZjF7bB+ADMWngAr7MMW24qcbizYzZ9MkxaAH205OLRzXiWGJtYkgRIEnSrzNtE+s4CxZeg 9NKDrKFx2xKV1pli4hqdxkQq5IaEfSBQgSlHHh6hNrRwaqAkPfDjBDimONIEyPSlK8DP5shpCF+Et 2suFpQ2fDAA413qvSqCUppesziln55ZKBg3rRqod8rJ3M/wZ3aP/tzXLXfVfNOFWZL8sImIqowjYv eE4oaCjg==; Received: from hch by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kXfNY-0006jP-FQ; Wed, 28 Oct 2020 06:56:16 +0000 Date: Wed, 28 Oct 2020 06:56:16 +0000 From: Christoph Hellwig To: Sebastian Andrzej Siewior Cc: Christoph Hellwig , Thomas Gleixner , David Runge , linux-rt-users@vger.kernel.org, Jens Axboe , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, Peter Zijlstra , Daniel Wagner Subject: Re: [PATCH RFC] blk-mq: Don't IPI requests on PREEMPT_RT Message-ID: <20201028065616.GA24449@infradead.org> References: <20201021175059.GA4989@hmbx> <20201023110400.bx3uzsb7xy5jtsea@linutronix.de> <20201023112130.GA23790@infradead.org> <20201023135219.mzzl76eqqy6tqwhe@linutronix.de> <20201027092606.GA20805@infradead.org> <20201027101102.cvczdb3mkvtoguo5@linutronix.de> <20201027160742.GA19073@infradead.org> <87eelj1tx0.fsf@nanos.tec.linutronix.de> <20201027172309.GA15004@infradead.org> <20201027205806.s7qau5xf4lzuslcu@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201027205806.s7qau5xf4lzuslcu@linutronix.de> 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: linux-kernel@vger.kernel.org > The remaining part is a switch to llist which avoids locking (IRQ > off/on) and it allows invoke the IPI/raise softirq only if something was > added. The entries are now processed in the reverse order but this > shouldn't matter right? For correctness it should not matter, but I think it could have performance implications. I think you'll have to throw in a llist_reverse_order. > I would split this into two patches (the blk_mq_complete_need_ipi() hunk > and the llist part) unless there are objections. Yes, please do.