From ab0809af0bee88b689ba289ec8c40aa2be3a17ec Mon Sep 17 00:00:00 2001 From: Kim Phillips Date: Tue, 22 Mar 2022 15:15:15 -0700 Subject: perf evsel: Improve AMD IBS (Instruction-Based Sampling) error handling messages MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Improve the error message returned on failed perf_event_open() on AMD systems when using IBS (Instruction-Based Sampling). Output of executing 'perf record -e ibs_op// true' as a non root user BEFORE this patch (perf will add the 'u' modifier at the end to exclude kernel/hypervisor sampling): The sys_perf_event_open() syscall returned with 22 (Invalid argument)for event (ibs_op//u). /bin/dmesg | grep -i perf may provide additional information. Output after: AMD IBS can't exclude kernel events. Try running at a higher privilege level. Output of executing 'sudo perf record -e ibs_op// true' BEFORE this patch: Error: The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (ibs_op//). /bin/dmesg | grep -i perf may provide additional information. Output after: Error: Invalid event (ibs_op//) in per-thread mode, enable system wide with '-a'. Folowing the suggestion: $ sudo perf record -a -e ibs_op// true [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 1.664 MB perf.data (194 samples) ] $ Signed-off-by: Kim Phillips Tested-by: Arnaldo Carvalho de Melo Cc: Alexander Shishkin Cc: Boris Ostrovsky Cc: Ian Rogers Cc: Jiri Olsa Cc: João Martins Cc: Konrad Rzeszutek Wilk Cc: Mark Rutland Cc: Michael Petlan Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Rafael J. Wysocki Cc: Ravi Bangoria Cc: Robert Richter Cc: Sandipan Das Cc: Song Liu Cc: Stephane Eranian Link: http://lore.kernel.org/lkml/20220322221517.2510440-12-eranian@google.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/evsel.c | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) (limited to 'tools') diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c index 5ecf8f836f30..2a1729e7aee4 100644 --- a/tools/perf/util/evsel.c +++ b/tools/perf/util/evsel.c @@ -2847,9 +2847,23 @@ static bool find_process(const char *name) return ret ? false : true; } +static bool is_amd(const char *arch, const char *cpuid) +{ + return arch && !strcmp("x86", arch) && cpuid && strstarts(cpuid, "AuthenticAMD"); +} + +static bool is_amd_ibs(struct evsel *evsel) +{ + return evsel->core.attr.precise_ip + || (evsel->pmu_name && !strncmp(evsel->pmu_name, "ibs", 3)); +} + int evsel__open_strerror(struct evsel *evsel, struct target *target, int err, char *msg, size_t size) { + struct perf_env *env = evsel__env(evsel); + const char *arch = perf_env__arch(env); + const char *cpuid = perf_env__cpuid(env); char sbuf[STRERR_BUFSIZE]; int printed = 0, enforced = 0; @@ -2953,6 +2967,17 @@ int evsel__open_strerror(struct evsel *evsel, struct target *target, return scnprintf(msg, size, "Invalid event (%s) in per-thread mode, enable system wide with '-a'.", evsel__name(evsel)); + if (is_amd(arch, cpuid)) { + if (is_amd_ibs(evsel)) { + if (evsel->core.attr.exclude_kernel) + return scnprintf(msg, size, + "AMD IBS can't exclude kernel events. Try running at a higher privilege level."); + if (!evsel->core.system_wide) + return scnprintf(msg, size, + "AMD IBS may only be available in system-wide/per-cpu mode. Try using -a, or -C and workload affinity"); + } + } + break; case ENODATA: return scnprintf(msg, size, "Cannot collect data source with the load latency event alone. " -- cgit v1.2.3