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 EC313C2BB9A for ; Thu, 17 Dec 2020 16:43:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B91732388E for ; Thu, 17 Dec 2020 16:43:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728182AbgLQQnw (ORCPT ); Thu, 17 Dec 2020 11:43:52 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57118 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728080AbgLQQnv (ORCPT ); Thu, 17 Dec 2020 11:43:51 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8E64BC061794 for ; Thu, 17 Dec 2020 08:43:11 -0800 (PST) Date: Thu, 17 Dec 2020 17:43:08 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1608223389; 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=fXCm6k0W027Mb8RYqeAY5zi85G+eofzAV5gJeZWu9zA=; b=sJbENBZllxsUK0vpYjNbq/67g6yX6rhzRo4o6PadlpLpBfWMXCYIm83BZtk4gLxGy4CGhE Zf9geaY8G1h33SLw6W8GCEO+LAZToJE9vUPpkbPFZ/fy1OYSGqCK/0rOL88nvBA4OmCUuq eWHJmx7XIwg3Kw6MG5bEaMyYeVq+ORO3n/oFuDY5gqcF/e7XTwOdQNGUa3yehB5xCN4mk5 rRpRGF9Kl12W5dejMKWWpGL8cFFeK5EFsHoOYGcSnQFHShIUYIH5PxZByOp7WnAxvX7LmK NGRlJwWEBbHgZAhiYCDLg1u1tVNV+HS5aJHSKGdQlZjf17kNNZV0FMSAW8xPeA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1608223389; 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=fXCm6k0W027Mb8RYqeAY5zi85G+eofzAV5gJeZWu9zA=; b=w5srlj8Ef3+Lij9SQjdnxNT9c/5rRXBHEeIqgt72gOd6sWIF9pP0WeGHNIYYd1fHG6gxMb mUH/wtLigIH2XJBQ== From: Sebastian Andrzej Siewior To: Christoph Hellwig Cc: Jens Axboe , linux-block@vger.kernel.org, Thomas Gleixner , Peter Zijlstra , Daniel Wagner , Mike Galbraith , Sagi Grimberg Subject: Re: [PATCH 2/3] blk-mq: Always complete remote completions requests in softirq Message-ID: <20201217164308.ueki3scv3oxt4uta@linutronix.de> References: <20201204191356.2516405-1-bigeasy@linutronix.de> <20201204191356.2516405-3-bigeasy@linutronix.de> <20201208131319.GB22219@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20201208131319.GB22219@infradead.org> Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 2020-12-08 13:13:19 [+0000], Christoph Hellwig wrote: > On Mon, Dec 07, 2020 at 04:52:57PM -0700, Jens Axboe wrote: > > On 12/4/20 12:13 PM, Sebastian Andrzej Siewior wrote: > > > Controllers with multiple queues have their IRQ-handelers pinned to a > > > CPU. The core shouldn't need to complete the request on a remote CPU. > > > > > > Remove this case and always raise the softirq to complete the request. > > > > I don't like this one at all, it'll add a softirq jump for the fast path > > for eg nvme devices. > > For the real fast path, that is either a polled queue or irq driven > queues that only map to a single CPU we are never reaching this code, > so I'm not too worried. Not that I'd complain about numbers, preferably > in the commit log. Did Daniel provide all the numbers you/Jens were looking for or do we still wait for some? Sebastian