Re: [PATCH 6/7] perf expr: Add metric literals for topology.

[Jiri Olsa <jolsa@redhat.com>]

On Fri, Nov 05, 2021 at 10:09:42AM -0700, Ian Rogers wrote:
> Allow the number of cpus, cores, dies and packages to be queried by a
> metric expression.
> 
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
>  tools/perf/tests/expr.c | 12 +++++++++++-
>  tools/perf/util/expr.c  | 27 +++++++++++++++++++++++++++
>  2 files changed, 38 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/perf/tests/expr.c b/tools/perf/tests/expr.c
> index 9ee2dc91c27b..0c09ccc76665 100644
> --- a/tools/perf/tests/expr.c
> +++ b/tools/perf/tests/expr.c
> @@ -66,7 +66,7 @@ int test__expr(struct test *t __maybe_unused, int subtest __maybe_unused)
>  {
>  	struct expr_id_data *val_ptr;
>  	const char *p;
> -	double val;
> +	double val, num_cpus, num_cores, num_dies, num_packages;
>  	int ret;
>  	struct expr_parse_ctx *ctx;
>  
> @@ -161,6 +161,16 @@ int test__expr(struct test *t __maybe_unused, int subtest __maybe_unused)
>  			NULL, ctx) == 0);
>  	TEST_ASSERT_VAL("find ids", hashmap__size(ctx->ids) == 0);
>  
> +	/* Test toplogy constants appear well ordered. */
> +	expr__ctx_clear(ctx);
> +	TEST_ASSERT_VAL("#num_cpus", expr__parse(&num_cpus, ctx, "#num_cpus") == 0);
> +	TEST_ASSERT_VAL("#num_cores", expr__parse(&num_cores, ctx, "#num_cores") == 0);
> +	TEST_ASSERT_VAL("#num_cpus >= #num_cores", num_cpus >= num_cores);
> +	TEST_ASSERT_VAL("#num_dies", expr__parse(&num_dies, ctx, "#num_dies") == 0);
> +	TEST_ASSERT_VAL("#num_cores >= #num_dies", num_cores >= num_dies);
> +	TEST_ASSERT_VAL("#num_packages", expr__parse(&num_packages, ctx, "#num_packages") == 0);
> +	TEST_ASSERT_VAL("#num_dies >= #num_packages", num_dies >= num_packages);
> +
>  	expr__ctx_free(ctx);
>  
>  	return 0;
> diff --git a/tools/perf/util/expr.c b/tools/perf/util/expr.c
> index 7464739c2890..15af8b8ef5e7 100644
> --- a/tools/perf/util/expr.c
> +++ b/tools/perf/util/expr.c
> @@ -5,6 +5,8 @@
>  #include <stdlib.h>
>  #include <string.h>
>  #include "metricgroup.h"
> +#include "cpumap.h"
> +#include "cputopo.h"
>  #include "debug.h"
>  #include "expr.h"
>  #include "expr-bison.h"
> @@ -375,9 +377,34 @@ double expr_id_data__value(const struct expr_id_data *data)
>  
>  double expr__get_literal(const char *literal)
>  {
> +	static struct cpu_topology *topology;
> +
>  	if (!strcmp("#smt_on", literal))
>  		return smt_on() > 0 ? 1.0 : 0.0;
>  
> +	if (!strcmp("#num_cpus", literal))
> +		return cpu__max_present_cpu();
> +
> +	/*
> +	 * Assume that topology strings are consistent, such as CPUs "0-1"
> +	 * wouldn't be listed as "0,1", and so after deduplication the number of
> +	 * these strings gives an indication of the number of packages, dies,
> +	 * etc.
> +	 */
> +	if (!topology) {
> +		topology = cpu_topology__new();

any chance we could propagate expr_scanner_ctx in here and store topology
to it and release it at the end? I think we have several places like this,
so it'd be nice not to make more if it's possible ;-)

thanks,
jirka

> +		if (!topology) {
> +			pr_err("Error creating CPU topology");
> +			return NAN;
> +		}
> +	}
> +	if (!strcmp("#num_packages", literal))
> +		return topology->package_cpus_lists;
> +	if (!strcmp("#num_dies", literal))
> +		return topology->die_cpus_lists;
> +	if (!strcmp("#num_cores", literal))
> +		return topology->core_cpus_lists;
> +
>  	pr_err("Unrecognized literal '%s'", literal);
>  	return NAN;
>  }
> -- 
> 2.34.0.rc0.344.g81b53c2807-goog
>