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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham 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 A23B0C4360F for ; Wed, 3 Apr 2019 17:16:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 54B5B205C9 for ; Wed, 3 Apr 2019 17:16:51 +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="FrV3Vkbj" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726372AbfDCRQt (ORCPT ); Wed, 3 Apr 2019 13:16:49 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:41786 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726074AbfDCRQt (ORCPT ); Wed, 3 Apr 2019 13:16:49 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Transfer-Encoding :Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To: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=YHQi/3e6+Nd2hmdPSPUhS2o9LcDAvjz7QnorLsrEaIA=; b=FrV3Vkbj94xDcrez4y+cFwZDvK 8Q8ZRS8AGtUWTig02ihcurV7zE/EgQoc/ERjGev3ApAPQ/t2ZuH9xyPjDqcUprs+2s3UEeTtCMfmJ Qp2IyMl9+4LzYyta6Csf5oPcbfHKzT7obMyQEu5qPVTlOHYv0YFP9yJV3kfQ8NCtkUlSd/rTemEyU MEqBmG5+TrRoDvy2uKcavz5Lzcs+BIhEXA/qMKJOt3+qjkT26ohY7+6L0iqMU0i07yv7PzRLbnYKR rjzyci7tmIaRgeRjaZGiZrOaTYwLFw2/wpfnGug8FzeaFOIK2OJHreUoSTDrQJSxSqLSBEroZlKI9 D0AY5Arg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1hBjV8-000255-3T; Wed, 03 Apr 2019 17:16:38 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 56840203C12DB; Wed, 3 Apr 2019 19:16:35 +0200 (CEST) Date: Wed, 3 Apr 2019 19:16:35 +0200 From: Peter Zijlstra To: Waiman Long Cc: Alex Kogan , linux@armlinux.org.uk, mingo@redhat.com, will.deacon@arm.com, arnd@arndb.de, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, bp@alien8.de, hpa@zytor.com, x86@kernel.org, steven.sistare@oracle.com, daniel.m.jordan@oracle.com, dave.dice@oracle.com, rahul.x.yadav@oracle.com Subject: Re: [PATCH v2 3/5] locking/qspinlock: Introduce CNA into the slow path of qspinlock Message-ID: <20190403171635.GM4038@hirez.programming.kicks-ass.net> References: <20190329152006.110370-1-alex.kogan@oracle.com> <20190329152006.110370-4-alex.kogan@oracle.com> <60a3a2d8-d222-73aa-2df1-64c9d3fa3241@redhat.com> <20190402094320.GM11158@hirez.programming.kicks-ass.net> <9ec3d8dc-d1e0-1b8a-5e00-ba92b9756c58@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <9ec3d8dc-d1e0-1b8a-5e00-ba92b9756c58@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 03, 2019 at 12:33:20PM -0400, Waiman Long wrote: > static inline void queued_spin_lock_slowpath(struct qspinlock *lock, u32 > val) > { >         if (static_branch_unlikely(&use_numa_spinlock)) >                 numa_queued_spin_lock_slowpath(lock, val); >         else    >                 native_queued_spin_lock_slowpath(lock, val); > } That's horrible for the exact reason you state. > Alternatively, we can also call numa_queued_spin_lock_slowpath() in > native_queued_spin_lock_slowpath() if we don't want to increase the code > size of spinlock call sites. Yeah, still don't much like that though, we're littering the fast path of that slow path with all sorts of crap.