Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935382AbaKNOAZ (ORCPT ); Fri, 14 Nov 2014 09:00:25 -0500 Received: from mga02.intel.com ([134.134.136.20]:4466 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934667AbaKNN7r (ORCPT ); Fri, 14 Nov 2014 08:59:47 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.07,386,1413270000"; d="scan'208";a="607847735" From: kan.liang@intel.com To: acme@kernel.org, jolsa@redhat.com, a.p.zijlstra@chello.nl, eranian@google.com Cc: linux-kernel@vger.kernel.org, mingo@redhat.com, paulus@samba.org, ak@linux.intel.com, Kan Liang Subject: [PATCH V3 1/3] perf tools: enable LBR call stack support Date: Fri, 14 Nov 2014 08:44:10 -0500 Message-Id: <1415972652-17310-2-git-send-email-kan.liang@intel.com> X-Mailer: git-send-email 1.8.3.2 In-Reply-To: <1415972652-17310-1-git-send-email-kan.liang@intel.com> References: <1415972652-17310-1-git-send-email-kan.liang@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Kan Liang Currently, there are two call chain recording options, fp and dwarf. Haswell has a new feature that utilizes the existing LBR facility to record call chains. So it provides the third options to record call chain. This patch enables the lbr call stack support. LBR call stack has some limitations. It reuses current LBR facility, so LBR call stack and branch record can not be enabled at the same time. It is only available for user callchain. However, LBR call stack can work on the user app which doesn't have frame-pointer or dwarf debug info compiled. It is a good alternative when nothing else works. Signed-off-by: Kan Liang --- tools/perf/Documentation/perf-record.txt | 8 +++++++- tools/perf/builtin-record.c | 6 +++--- tools/perf/builtin-report.c | 2 ++ tools/perf/util/callchain.c | 10 +++++++++- tools/perf/util/callchain.h | 1 + tools/perf/util/evsel.c | 21 +++++++++++++++++++-- 6 files changed, 41 insertions(+), 7 deletions(-) diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt index 398f8d5..03d9939 100644 --- a/tools/perf/Documentation/perf-record.txt +++ b/tools/perf/Documentation/perf-record.txt @@ -100,13 +100,19 @@ OPTIONS implies -g. Allows specifying "fp" (frame pointer) or "dwarf" - (DWARF's CFI - Call Frame Information) as the method to collect + (DWARF's CFI - Call Frame Information) or "lbr" + (Hardware Last Branch Record facility) as the method to collect the information used to show the call graphs. In some systems, where binaries are build with gcc --fomit-frame-pointer, using the "fp" method will produce bogus call graphs, using "dwarf", if available (perf tools linked to the libunwind library) should be used instead. + Using the "lbr" method doesn't require any compiler options. It + will produce call graphs from the hardware LBR registers. The + main limition is that it is only available on new Intel + platforms, such as Haswell. It can only get user call chain. It + doesn't work with branch stack sampling at the same time. -q:: --quiet:: diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c index 582c4da..e486627 100644 --- a/tools/perf/builtin-record.c +++ b/tools/perf/builtin-record.c @@ -639,7 +639,7 @@ error: static void callchain_debug(void) { - static const char *str[CALLCHAIN_MAX] = { "NONE", "FP", "DWARF" }; + static const char *str[CALLCHAIN_MAX] = { "NONE", "FP", "DWARF", "LBR" }; pr_debug("callchain: type %s\n", str[callchain_param.record_mode]); @@ -725,9 +725,9 @@ static struct record record = { #define CALLCHAIN_HELP "setup and enables call-graph (stack chain/backtrace) recording: " #ifdef HAVE_DWARF_UNWIND_SUPPORT -const char record_callchain_help[] = CALLCHAIN_HELP "fp dwarf"; +const char record_callchain_help[] = CALLCHAIN_HELP "fp dwarf lbr"; #else -const char record_callchain_help[] = CALLCHAIN_HELP "fp"; +const char record_callchain_help[] = CALLCHAIN_HELP "fp lbr"; #endif /* diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c index 140a6cd..43babdb 100644 --- a/tools/perf/builtin-report.c +++ b/tools/perf/builtin-report.c @@ -261,6 +261,8 @@ static int report__setup_sample_type(struct report *rep) if ((sample_type & PERF_SAMPLE_REGS_USER) && (sample_type & PERF_SAMPLE_STACK_USER)) callchain_param.record_mode = CALLCHAIN_DWARF; + else if (sample_type & PERF_SAMPLE_BRANCH_STACK) + callchain_param.record_mode = CALLCHAIN_LBR; else callchain_param.record_mode = CALLCHAIN_FP; } diff --git a/tools/perf/util/callchain.c b/tools/perf/util/callchain.c index 38da69c..138c5d6 100644 --- a/tools/perf/util/callchain.c +++ b/tools/perf/util/callchain.c @@ -77,7 +77,7 @@ int parse_callchain_record_opt(const char *arg) ret = 0; } else pr_err("callchain: No more arguments " - "needed for -g fp\n"); + "needed for --call-graph fp\n"); break; #ifdef HAVE_DWARF_UNWIND_SUPPORT @@ -97,6 +97,14 @@ int parse_callchain_record_opt(const char *arg) callchain_param.dump_size = size; } #endif /* HAVE_DWARF_UNWIND_SUPPORT */ + } else if (!strncmp(name, "lbr", sizeof("lbr"))) { + if (!strtok_r(NULL, ",", &saveptr)) { + callchain_param.record_mode = CALLCHAIN_LBR; + ret = 0; + } else + pr_err("callchain: No more arguments " + "needed for --call-graph lbr\n"); + break; } else { pr_err("callchain: Unknown --call-graph option " "value: %s\n", arg); diff --git a/tools/perf/util/callchain.h b/tools/perf/util/callchain.h index 3e1ed15..a60a7b5 100644 --- a/tools/perf/util/callchain.h +++ b/tools/perf/util/callchain.h @@ -11,6 +11,7 @@ enum perf_call_graph_mode { CALLCHAIN_NONE, CALLCHAIN_FP, CALLCHAIN_DWARF, + CALLCHAIN_LBR, CALLCHAIN_MAX }; diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c index 12b4396..7cbe2e9 100644 --- a/tools/perf/util/evsel.c +++ b/tools/perf/util/evsel.c @@ -537,13 +537,30 @@ int perf_evsel__group_desc(struct perf_evsel *evsel, char *buf, size_t size) } static void -perf_evsel__config_callgraph(struct perf_evsel *evsel) +perf_evsel__config_callgraph(struct perf_evsel *evsel, + struct record_opts *opts) { bool function = perf_evsel__is_function_event(evsel); struct perf_event_attr *attr = &evsel->attr; perf_evsel__set_sample_bit(evsel, CALLCHAIN); + if (callchain_param.record_mode == CALLCHAIN_LBR) { + if (!opts->branch_stack) { + perf_evsel__set_sample_bit(evsel, BRANCH_STACK); + attr->branch_sample_type = PERF_SAMPLE_BRANCH_USER | + PERF_SAMPLE_BRANCH_CALL_STACK; + if (attr->exclude_user) { + attr->exclude_user = 0; + + pr_warning("LBR callstack option is only available" + " to get user callchain information." + " Force exclude_user to 0.\n"); + } + } else + pr_info("Cannot use LBR callstack with branch stack\n"); + } + if (callchain_param.record_mode == CALLCHAIN_DWARF) { if (!function) { perf_evsel__set_sample_bit(evsel, REGS_USER); @@ -659,7 +676,7 @@ void perf_evsel__config(struct perf_evsel *evsel, struct record_opts *opts) } if (callchain_param.enabled && !evsel->no_aux_samples) - perf_evsel__config_callgraph(evsel); + perf_evsel__config_callgraph(evsel, opts); if (target__has_cpu(&opts->target)) perf_evsel__set_sample_bit(evsel, CPU); -- 1.8.3.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/