From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752589Ab3INGSY (ORCPT ); Sat, 14 Sep 2013 02:18:24 -0400 Received: from mga11.intel.com ([192.55.52.93]:43653 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751234Ab3INGSX (ORCPT ); Sat, 14 Sep 2013 02:18:23 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.90,902,1371106800"; d="scan'208";a="401571615" From: Andi Kleen To: mingo@kernel.org Cc: hpa@zytor.com, linux-kernel@vger.kernel.org, peterz@infradead.org, tglx@linutronix.de, linux-tip-commits@vger.kernel.org Subject: Re: [tip:perf/core] perf/x86/intel: Clean-up/reduce PEBS code References: Date: Fri, 13 Sep 2013 23:18:21 -0700 In-Reply-To: (tip-bot for Peter Zijlstra's message of "Thu, 12 Sep 2013 11:04:44 -0700") Message-ID: <87mwng53ki.fsf@tassilo.jf.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org tip-bot for Peter Zijlstra writes: > + > + at = (struct pebs_record_nhm *)(unsigned long)ds->pebs_buffer_base; > + top = (struct pebs_record_nhm *)(unsigned long)ds->pebs_index; > > ds->pebs_index = ds->pebs_buffer_base; > > + n = (top - at) / x86_pmu.pebs_record_size; This adds a full slow division to the PEBS hot path. Does not seem like a improvement to me. -Andi -- ak@linux.intel.com -- Speaking for myself only