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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 54CBBC2D0DB for ; Wed, 22 Jan 2020 09:56:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 284612465A for ; Wed, 22 Jan 2020 09:56:47 +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="HsXlNynE" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731185AbgAVJ4q (ORCPT ); Wed, 22 Jan 2020 04:56:46 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:52700 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730479AbgAVJ4l (ORCPT ); Wed, 22 Jan 2020 04:56:41 -0500 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: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=mn6+IrA1OMHHWbypsNWVR2N6HpOhrjkcIFslmxed/eo=; b=HsXlNynEa7rAEPUuseLjSSMDy Q2ZIa+JF/SWMm8NTGS8kjTYTm7k0lmwRA2N26GdpaTOKT7x6Rl74bbquaC31sEv1UEuVdTeoACjpE haJLzgbT37Mo4QRNy5zwDjdV2PVjIiJD8NA5dTQzxG9CxVJjPsTgT85KxGpC3f1ErrKC+g93uNeCb fMuc+IqdAHHLniSmW61yM4llntPLgFo+BhqrJ2PXXNxJVoEUBE4qmEH5qhabFL0skPb+Q4VfLPqiW uvadfmJBWkox6SFdYK2MSEmSql0HHYH9azJA1+tZSF5HROGmtQK6z/OpK1WAz7jom9SSmk3lhOCzq 6UpyNdydA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1iuCkL-00026Y-Ic; Wed, 22 Jan 2020 09:56:26 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 6C2543060D3; Wed, 22 Jan 2020 10:54:43 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id EE68D20983E31; Wed, 22 Jan 2020 10:56:22 +0100 (CET) Date: Wed, 22 Jan 2020 10:56:22 +0100 From: Peter Zijlstra To: Alex Kogan Cc: linux@armlinux.org.uk, mingo@redhat.com, will.deacon@arm.com, arnd@arndb.de, longman@redhat.com, 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, guohanjun@huawei.com, jglauber@marvell.com, steven.sistare@oracle.com, daniel.m.jordan@oracle.com, dave.dice@oracle.com Subject: Re: [PATCH v8 5/5] locking/qspinlock: Introduce the shuffle reduction optimization into CNA Message-ID: <20200122095622.GS14914@hirez.programming.kicks-ass.net> References: <20191230194042.67789-1-alex.kogan@oracle.com> <20191230194042.67789-6-alex.kogan@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191230194042.67789-6-alex.kogan@oracle.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 Mon, Dec 30, 2019 at 02:40:42PM -0500, Alex Kogan wrote: > @@ -251,8 +281,11 @@ __always_inline u32 cna_pre_scan(struct qspinlock *lock, > struct cna_node *cn = (struct cna_node *)node; > > cn->pre_scan_result = > - cn->intra_count == intra_node_handoff_threshold ? > - FLUSH_SECONDARY_QUEUE : cna_scan_main_queue(node, node); > + (node->locked <= 1 && probably(SHUFFLE_REDUCTION_PROB_ARG)) ? > + PASS_LOCK_IMMEDIATELY : > + cn->intra_count == intra_node_handoff_threshold ? > + FLUSH_SECONDARY_QUEUE : > + cna_scan_main_queue(node, node); > > return 0; > } Let me just, once again, remind people that the Linux Kernel is not part of the Obfuscated C code contest. > Reviewed-by: Steve Sistare Seriously, in what universe is that actually readable code? Steve quick, say what it does.