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perf metrics: Add has_pmem literal

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Add literal so that if nvdimms aren't installed we can record fewer
events.  The file detection mechanism was suggested by Dan Williams
<dan.j.williams@intel.com> in:

  https://lore.kernel.org/linux-perf-users/641bbe1eced26_1b98bb29440@dwillia2-xfh.jf.intel.com.notmuch/

Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Caleb Biggers <caleb.biggers@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Edward Baker <edward.baker@intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Perry Taylor <perry.taylor@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Samantha Alt <samantha.alt@intel.com>
Cc: Weilin Wang <weilin.wang@intel.com>
Cc: Xing Zhengjun <zhengjun.xing@linux.intel.com>
Link: https://lore.kernel.org/r/20230324072218.181880-2-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Ian Rogers 2023-03-24 00:22:17 -07:00 committed by Arnaldo Carvalho de Melo
parent e559b6f53b
commit c3bf86f11d
1 changed files with 19 additions and 0 deletions
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19
tools/perf/util/expr.c
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@ -14,6 +14,7 @@
#include "util/hashmap.h"
#include "smt.h"
#include "tsc.h"
#include <api/fs/fs.h>
#include <linux/err.h>
#include <linux/kernel.h>
#include <linux/zalloc.h>
@ -400,6 +401,20 @@ double arch_get_tsc_freq(void)
}
#endif
static double has_pmem(void)
{
static bool has_pmem, cached;
const char *sysfs = sysfs__mountpoint();
char path[PATH_MAX];
if (!cached) {
snprintf(path, sizeof(path), "%s/firmware/acpi/tables/NFIT", sysfs);
has_pmem = access(path, F_OK) == 0;
cached = true;
}
return has_pmem ? 1.0 : 0.0;
}
double expr__get_literal(const char *literal, const struct expr_scanner_ctx *ctx)
{
const struct cpu_topology *topology;
@ -449,6 +464,10 @@ double expr__get_literal(const char *literal, const struct expr_scanner_ctx *ctx
result = perf_pmu__cpu_slots_per_cycle();
goto out;
}
if (!strcmp("#has_pmem", literal)) {
result = has_pmem();
goto out;
}
pr_err("Unrecognized literal '%s'", literal);
out: