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Message-ID: <eb1c058c-f84f-ae94-ced6-92f22b6d9b69@intel.com>
Date: Mon, 3 Apr 2023 07:51:01 +0300
From: Adrian Hunter <adrian.hunter@...el.com>
To: Namhyung Kim <namhyung@...nel.org>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Jiri Olsa <jolsa@...nel.org>
Cc: Ian Rogers <irogers@...gle.com>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...nel.org>,
LKML <linux-kernel@...r.kernel.org>,
linux-perf-users@...r.kernel.org,
Kan Liang <kan.liang@...ux.intel.com>,
Leo Yan <leo.yan@...aro.org>
Subject: Re: [PATCH 9/9] perf intel-pt: Use perf_pmu__scan_file_at() if
possible
On 31/03/23 23:29, Namhyung Kim wrote:
> Intel-PT calls perf_pmu__scan_file() a lot, let's use relative address
> when it accesses multiple files at one place.
>
> Signed-off-by: Namhyung Kim <namhyung@...nel.org>
Acked-by: Adrian Hunter <adrian.hunter@...el.com>
> ---
> tools/perf/arch/x86/util/intel-pt.c | 52 ++++++++++++++++++-----------
> 1 file changed, 32 insertions(+), 20 deletions(-)
>
> diff --git a/tools/perf/arch/x86/util/intel-pt.c b/tools/perf/arch/x86/util/intel-pt.c
> index 1e39a034cee9..2cff11de9d8a 100644
> --- a/tools/perf/arch/x86/util/intel-pt.c
> +++ b/tools/perf/arch/x86/util/intel-pt.c
> @@ -194,16 +194,19 @@ static u64 intel_pt_default_config(struct perf_pmu *intel_pt_pmu)
> int pos = 0;
> u64 config;
> char c;
> + int dirfd;
> +
> + dirfd = perf_pmu__event_source_devices_fd();
>
> pos += scnprintf(buf + pos, sizeof(buf) - pos, "tsc");
>
> - if (perf_pmu__scan_file(intel_pt_pmu, "caps/mtc", "%d",
> - &mtc) != 1)
> + if (perf_pmu__scan_file_at(intel_pt_pmu, dirfd, "caps/mtc", "%d",
> + &mtc) != 1)
> mtc = 1;
>
> if (mtc) {
> - if (perf_pmu__scan_file(intel_pt_pmu, "caps/mtc_periods", "%x",
> - &mtc_periods) != 1)
> + if (perf_pmu__scan_file_at(intel_pt_pmu, dirfd, "caps/mtc_periods", "%x",
> + &mtc_periods) != 1)
> mtc_periods = 0;
> if (mtc_periods) {
> mtc_period = intel_pt_pick_bit(mtc_periods, 3);
> @@ -212,13 +215,13 @@ static u64 intel_pt_default_config(struct perf_pmu *intel_pt_pmu)
> }
> }
>
> - if (perf_pmu__scan_file(intel_pt_pmu, "caps/psb_cyc", "%d",
> - &psb_cyc) != 1)
> + if (perf_pmu__scan_file_at(intel_pt_pmu, dirfd, "caps/psb_cyc", "%d",
> + &psb_cyc) != 1)
> psb_cyc = 1;
>
> if (psb_cyc && mtc_periods) {
> - if (perf_pmu__scan_file(intel_pt_pmu, "caps/psb_periods", "%x",
> - &psb_periods) != 1)
> + if (perf_pmu__scan_file_at(intel_pt_pmu, dirfd, "caps/psb_periods", "%x",
> + &psb_periods) != 1)
> psb_periods = 0;
> if (psb_periods) {
> psb_period = intel_pt_pick_bit(psb_periods, 3);
> @@ -227,8 +230,8 @@ static u64 intel_pt_default_config(struct perf_pmu *intel_pt_pmu)
> }
> }
>
> - if (perf_pmu__scan_file(intel_pt_pmu, "format/pt", "%c", &c) == 1 &&
> - perf_pmu__scan_file(intel_pt_pmu, "format/branch", "%c", &c) == 1)
> + if (perf_pmu__scan_file_at(intel_pt_pmu, dirfd, "format/pt", "%c", &c) == 1 &&
> + perf_pmu__scan_file_at(intel_pt_pmu, dirfd, "format/branch", "%c", &c) == 1)
> pos += scnprintf(buf + pos, sizeof(buf) - pos, ",pt,branch");
>
> pr_debug2("%s default config: %s\n", intel_pt_pmu->name, buf);
> @@ -236,6 +239,7 @@ static u64 intel_pt_default_config(struct perf_pmu *intel_pt_pmu)
> intel_pt_parse_terms(intel_pt_pmu->name, &intel_pt_pmu->format, buf,
> &config);
>
> + close(dirfd);
> return config;
> }
>
> @@ -488,7 +492,7 @@ static void intel_pt_valid_str(char *str, size_t len, u64 valid)
> }
> }
>
> -static int intel_pt_val_config_term(struct perf_pmu *intel_pt_pmu,
> +static int intel_pt_val_config_term(struct perf_pmu *intel_pt_pmu, int dirfd,
> const char *caps, const char *name,
> const char *supported, u64 config)
> {
> @@ -498,11 +502,11 @@ static int intel_pt_val_config_term(struct perf_pmu *intel_pt_pmu,
> u64 bits;
> int ok;
>
> - if (perf_pmu__scan_file(intel_pt_pmu, caps, "%llx", &valid) != 1)
> + if (perf_pmu__scan_file_at(intel_pt_pmu, dirfd, caps, "%llx", &valid) != 1)
> valid = 0;
>
> if (supported &&
> - perf_pmu__scan_file(intel_pt_pmu, supported, "%d", &ok) == 1 && !ok)
> + perf_pmu__scan_file_at(intel_pt_pmu, dirfd, supported, "%d", &ok) == 1 && !ok)
> valid = 0;
>
> valid |= 1;
> @@ -531,37 +535,45 @@ static int intel_pt_val_config_term(struct perf_pmu *intel_pt_pmu,
> static int intel_pt_validate_config(struct perf_pmu *intel_pt_pmu,
> struct evsel *evsel)
> {
> - int err;
> + int err, dirfd;
> char c;
>
> if (!evsel)
> return 0;
>
> + dirfd = perf_pmu__event_source_devices_fd();
> + if (dirfd < 0)
> + return dirfd;
> +
> /*
> * If supported, force pass-through config term (pt=1) even if user
> * sets pt=0, which avoids senseless kernel errors.
> */
> - if (perf_pmu__scan_file(intel_pt_pmu, "format/pt", "%c", &c) == 1 &&
> + if (perf_pmu__scan_file_at(intel_pt_pmu, dirfd, "format/pt", "%c", &c) == 1 &&
> !(evsel->core.attr.config & 1)) {
> pr_warning("pt=0 doesn't make sense, forcing pt=1\n");
> evsel->core.attr.config |= 1;
> }
>
> - err = intel_pt_val_config_term(intel_pt_pmu, "caps/cycle_thresholds",
> + err = intel_pt_val_config_term(intel_pt_pmu, dirfd, "caps/cycle_thresholds",
> "cyc_thresh", "caps/psb_cyc",
> evsel->core.attr.config);
> if (err)
> - return err;
> + goto out;
>
> - err = intel_pt_val_config_term(intel_pt_pmu, "caps/mtc_periods",
> + err = intel_pt_val_config_term(intel_pt_pmu, dirfd, "caps/mtc_periods",
> "mtc_period", "caps/mtc",
> evsel->core.attr.config);
> if (err)
> - return err;
> + goto out;
>
> - return intel_pt_val_config_term(intel_pt_pmu, "caps/psb_periods",
> + err = intel_pt_val_config_term(intel_pt_pmu, dirfd, "caps/psb_periods",
> "psb_period", "caps/psb_cyc",
> evsel->core.attr.config);
> +
> +out:
> + close(dirfd);
> + return err;
> }
>
> static void intel_pt_config_sample_mode(struct perf_pmu *intel_pt_pmu,
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