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=-0.8 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 506A1C433DF for ; Tue, 30 Jun 2020 16:40:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 272F020723 for ; Tue, 30 Jun 2020 16:40:39 +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="wRLmPi/O" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389318AbgF3Qkh (ORCPT ); Tue, 30 Jun 2020 12:40:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45654 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732049AbgF3Qkh (ORCPT ); Tue, 30 Jun 2020 12:40:37 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DE8B7C061755 for ; Tue, 30 Jun 2020 09:40:36 -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=yKdZNHoBg53b/hVeYXoFqzfvLaS4RH0SHvXu7VLjagI=; b=wRLmPi/OzHA7KEt8qXKQj4l7zQ J0L0NG/t2hgsb7N5ObUMyi/tK6L3No7CwP9Rr3mkz2QH1ASsMPlXmruW3v+s3mQcoowyOYsGNo8nn VT6cjW3AGbJ/R97WpfxXpSfUAPnBLM1kfvA3/r9NAXyIL89rKUPC4HsOV2RmzoXUMKt4J8WoVeZ1Y wcuS7/SxmkO3vx602OJiCg6s2XJoQFcigLfPNgUr29G2i+/g/X4KfU2VVg0uGhRzuVm6ogRQq9xbx 7CBqf+Ws19Z3oedJmwL0zRU1rbM2Ap0UobCSpjUmiywKqFp6MIFDt4uS5OqwwvOvB6jeu4f7zqv13 FpI03pDg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jqJIa-0001mQ-IP; Tue, 30 Jun 2020 16:39:56 +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 92BDA306064; Tue, 30 Jun 2020 18:39:54 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 7FC0C20CF3986; Tue, 30 Jun 2020 18:39:54 +0200 (CEST) Date: Tue, 30 Jun 2020 18:39:54 +0200 From: Peter Zijlstra To: "Liang, Kan" Cc: mingo@redhat.com, acme@kernel.org, tglx@linutronix.de, bp@alien8.de, x86@kernel.org, linux-kernel@vger.kernel.org, mark.rutland@arm.com, alexander.shishkin@linux.intel.com, jolsa@redhat.com, namhyung@kernel.org, dave.hansen@intel.com, yu-cheng.yu@intel.com, bigeasy@linutronix.de, gorcunov@gmail.com, hpa@zytor.com, alexey.budankov@linux.intel.com, eranian@google.com, ak@linux.intel.com, like.xu@linux.intel.com, yao.jin@linux.intel.com, wei.w.wang@intel.com Subject: Re: [PATCH V2 08/23] perf/x86: Expose CPUID enumeration bits for arch LBR Message-ID: <20200630163954.GY4817@hirez.programming.kicks-ass.net> References: <1593195620-116988-1-git-send-email-kan.liang@linux.intel.com> <1593195620-116988-9-git-send-email-kan.liang@linux.intel.com> <20200630150154.GS4781@hirez.programming.kicks-ass.net> <211b4d70-eec5-4577-45fb-99435023cab8@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <211b4d70-eec5-4577-45fb-99435023cab8@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 30, 2020 at 11:36:29AM -0400, Liang, Kan wrote: > > Why keep the full CPUID leaf here? What's wrong with something like: > > > > unsigned int lbr_depth_mask:8; > > unsigned int lbr_deep_c_reset:1; > > unsigned int lbr_lip:1; > > unsigned int lbr_cpl:1; > > unsigned int lbr_filter:1; > > unsigned int lbr_call_stack:1; > > unsigned int lbr_mispred:1; > > unsigned int lbr_timed_lbr:1; > > unsigned int lbr_br_type:1; > > > > That's only 2 bytes, instead of 24. > > Yes, it can save the space. > I will add some codes in patch 14 to initialize these items in > intel_pmu_arch_lbr_init(). It also makes stuff like: > + if (!x86_pmu.lbr_ebx.split.lbr_cpl || > + !x86_pmu.lbr_ebx.split.lbr_filter || > + !x86_pmu.lbr_ebx.split.lbr_call_stack) eminently more readable.