Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752094AbdFOTTa (ORCPT ); Thu, 15 Jun 2017 15:19:30 -0400 Received: from mail-io0-f177.google.com ([209.85.223.177]:34601 "EHLO mail-io0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750830AbdFOTT2 (ORCPT ); Thu, 15 Jun 2017 15:19:28 -0400 MIME-Version: 1.0 In-Reply-To: References: <1497534989-29231-1-git-send-email-eranian@google.com> <1497534989-29231-3-git-send-email-eranian@google.com> <37D7C6CF3E00A74B8858931C1DB2F0775370DC74@SHSMSX103.ccr.corp.intel.com> From: Stephane Eranian Date: Thu, 15 Jun 2017 12:19:27 -0700 Message-ID: Subject: Re: [PATCH 2/5] perf/x86: add PERF_SAMPLE_SKID_IP support for X86 PEBS To: "Liang, Kan" Cc: "linux-kernel@vger.kernel.org" , "acme@redhat.com" , "peterz@infradead.org" , "mingo@elte.hu" , "ak@linux.intel.com" , "jolsa@redhat.com" Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1814 Lines: 47 Hi, On Thu, Jun 15, 2017 at 9:39 AM, Stephane Eranian wrote: > On Thu, Jun 15, 2017 at 8:40 AM, Liang, Kan wrote: >> >> >>> This patch adds support for SKID_IP to Intel x86 processors in PEBS mode. In >>> that case, the off-by-1 IP from PEBS is returned in the SKID_IP field. >> >> It looks we can only get different skid_ip and ip with :pp event (attr.precise = 2). >> With the :p event (attr.precise = 1), the skid_ip and ip are the same. Right? >> > Correct, because skid_ip would be equal to the pebs->ip. > To be more precise, you can always specify PERF_SAMPLE_SKID_IP with any event or sampling mode. By default, the value saved in each sample will be the same as the one used for PERF_SAMPLE_IP. On Intel x86, it only differs with precise mode=2 for events supporting PEBS. >>> Signed-off-by: Stephane Eranian >>> --- >>> arch/x86/events/intel/ds.c | 7 +++++++ >>> 1 file changed, 7 insertions(+) >>> >>> diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c index >>> c6d23ffe422d..ee17de5d6b8d 100644 >>> --- a/arch/x86/events/intel/ds.c >>> +++ b/arch/x86/events/intel/ds.c >>> @@ -1169,6 +1169,13 @@ static void setup_pebs_sample_data(struct >>> perf_event *event, >>> x86_pmu.intel_cap.pebs_format >= 1) >>> data->addr = pebs->dla; >>> >>> + /* >>> + * unmodified, skid IP which is guaranteed to be the next >>> + * dyanmic instruction >>> + */ >>> + if (sample_type & PERF_SAMPLE_SKID_IP) >>> + data->skid_ip = pebs->ip; >>> + >>> if (x86_pmu.intel_cap.pebs_format >= 2) { >>> /* Only set the TSX weight when no memory weight. */ >>> if ((sample_type & PERF_SAMPLE_WEIGHT) && !fll) >>> -- >>> 2.13.1.518.g3df882009-goog >>