Re: [PATCH v2] perf evsel amd: Fix IBS error message
From: Namhyung Kim
Date: Mon Jun 26 2023 - 19:05:18 EST
Hi Ravi,
On Mon, Jun 26, 2023 at 3:40 AM Ravi Bangoria <ravi.bangoria@xxxxxxx> wrote:
>
> AMD IBS can do per-process profiling[1] and is no longer restricted to
> per-cpu or systemwide only. Remove stale error message. Also, checking
> just exclude_kernel is not sufficient since IBS does not support any
> privilege filters. So include all exclude_* checks. And finally, move
> these checks under tools/perf/arch/x86/ from generic code.
>
> Before:
> $ sudo ./perf record -e ibs_op//k -C 0
> Error:
> AMD IBS may only be available in system-wide/per-cpu mode. Try
> using -a, or -C and workload affinity
>
> After:
> $ sudo ./perf record -e ibs_op//k -C 0
> Error:
> AMD IBS doesn't support privilege filtering. Try again with
> exclude_{kernel|user|hv|idle|host|guest}=0.
Can we have more user-friendly messages like below?
"Try again without the privilege modifiers like 'k' at the end."
>
> Signed-off-by: Ravi Bangoria <ravi.bangoria@xxxxxxx>
> ---
> v1: https://lore.kernel.org/r/20230621062359.201-1-ravi.bangoria@xxxxxxx
> v1->v2:
> - Check all exclude_* flags not just exclude_kernel
> - Move AMD specific checks under tools/perf/arch/x86/
>
> tools/perf/arch/x86/util/evsel.c | 25 +++++++++++++++++++++++++
> tools/perf/util/evsel.c | 30 +++++++++---------------------
> tools/perf/util/evsel.h | 1 +
> 3 files changed, 35 insertions(+), 21 deletions(-)
>
> diff --git a/tools/perf/arch/x86/util/evsel.c b/tools/perf/arch/x86/util/evsel.c
> index 512c2d885d24..9a7141c5a4ea 100644
> --- a/tools/perf/arch/x86/util/evsel.c
> +++ b/tools/perf/arch/x86/util/evsel.c
> @@ -102,3 +102,28 @@ void arch__post_evsel_config(struct evsel *evsel, struct perf_event_attr *attr)
> }
> }
> }
> +
> +int arch_evsel__open_strerror(struct evsel *evsel, char *msg, size_t size)
> +{
> + if (!x86__is_amd_cpu())
> + return 0;
> +
> + if (!evsel->core.attr.precise_ip &&
> + !(evsel->pmu_name && !strncmp(evsel->pmu_name, "ibs", 3)))
> + return 0;
> +
> + /* More verbose IBS errors. */
> + if (evsel->core.attr.exclude_kernel || evsel->core.attr.exclude_user ||
> + evsel->core.attr.exclude_hv || evsel->core.attr.exclude_idle ||
> + evsel->core.attr.exclude_host || evsel->core.attr.exclude_guest) {
> + return scnprintf(msg, size, "AMD IBS doesn't support privilege filtering. Try "
> + "again with exclude_{kernel|user|hv|idle|host|guest}=0.");
> + }
> +
> + if (!evsel->core.attr.sample_period) {
> + return scnprintf(msg, size, "AMD IBS doesn't support counting mode. Try "
> + "again with sample_{period|freq} with non-zero value.");
Is this for perf stat? We don't allow zero period for perf record.
$ perf record -F 0 true
frequency and count are zero, aborting
Then maybe it can say: "IBS doesn't support perf stat, Use perf record."
Thanks,
Namhyung
> + }
> +
> + return 0;
> +}
> diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> index f607b5bddc76..762e2b2634a5 100644
> --- a/tools/perf/util/evsel.c
> +++ b/tools/perf/util/evsel.c
> @@ -2924,25 +2924,19 @@ static bool find_process(const char *name)
> return ret ? false : true;
> }
>
> -static bool is_amd(const char *arch, const char *cpuid)
> +int __weak arch_evsel__open_strerror(struct evsel *evsel __maybe_unused,
> + char *msg __maybe_unused,
> + size_t size __maybe_unused)
> {
> - 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));
> + return 0;
> }
>
> 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;
> + int ret;
>
> switch (err) {
> case EPERM:
> @@ -3044,16 +3038,6 @@ 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:
> @@ -3063,6 +3047,10 @@ int evsel__open_strerror(struct evsel *evsel, struct target *target,
> break;
> }
>
> + ret = arch_evsel__open_strerror(evsel, msg, size);
> + if (ret)
> + return ret;
> +
> return scnprintf(msg, size,
> "The sys_perf_event_open() syscall returned with %d (%s) for event (%s).\n"
> "/bin/dmesg | grep -i perf may provide additional information.\n",
> diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
> index 9f06d6cd5379..848534ec74fa 100644
> --- a/tools/perf/util/evsel.h
> +++ b/tools/perf/util/evsel.h
> @@ -311,6 +311,7 @@ void evsel__set_sample_id(struct evsel *evsel, bool use_sample_identifier);
>
> void arch_evsel__set_sample_weight(struct evsel *evsel);
> void arch__post_evsel_config(struct evsel *evsel, struct perf_event_attr *attr);
> +int arch_evsel__open_strerror(struct evsel *evsel, char *msg, size_t size);
>
> int evsel__set_filter(struct evsel *evsel, const char *filter);
> int evsel__append_tp_filter(struct evsel *evsel, const char *filter);
> --
> 2.41.0
>