Commit 09b73fe9 authored by Ian Rogers's avatar Ian Rogers Committed by Arnaldo Carvalho de Melo
Browse files

perf smt: Compute SMT from topology 



The topology records sibling threads. Rather than computing SMT using
siblings in sysfs, reuse the values in topology. This only applies
when the file smt/active isn't available.

Signed-off-by: default avatarIan Rogers <irogers@google.com>
Cc: Ahmad Yasin <ahmad.yasin@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Caleb Biggers <caleb.biggers@intel.com>
Cc: Florian Fischer <florian.fischer@muhq.space>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Garry <john.garry@huawei.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Kshipra Bopardikar <kshipra.bopardikar@intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Miaoqian Lin <linmq006@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Perry Taylor <perry.taylor@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Richter <tmricht@linux.ibm.com>
Cc: Xing Zhengjun <zhengjun.xing@linux.intel.com>
Link: https://lore.kernel.org/r/20220831174926.579643-4-irogers@google.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 1a6abdde

tools/perf/tests/expr.c

+15 −9
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

#include "util/cputopo.h"

#include "util/debug.h"

#include "util/expr.h"

#include "util/header.h"
@@ -154,15 +155,20 @@ static int test__expr(struct test_suite *t __maybe_unused, int subtest __maybe_u 
						    (void **)&val_ptr));



	/* Only EVENT1 or EVENT2 need be measured depending on the value of smt_on. */

	{

		struct cpu_topology *topology = cpu_topology__new();

		bool smton = smt_on(topology);



		cpu_topology__delete(topology);

		expr__ctx_clear(ctx);

		TEST_ASSERT_VAL("find ids",

				expr__find_ids("EVENT1 if #smt_on else EVENT2",

					NULL, ctx) == 0);

		TEST_ASSERT_VAL("find ids", hashmap__size(ctx->ids) == 1);

		TEST_ASSERT_VAL("find ids", hashmap__find(ctx->ids,

						  smt_on() ? "EVENT1" : "EVENT2",

							  smton ? "EVENT1" : "EVENT2",

							  (void **)&val_ptr));



	}

	/* The expression is a constant 1.0 without needing to evaluate EVENT1. */

	expr__ctx_clear(ctx);

	TEST_ASSERT_VAL("find ids",

tools/perf/util/cputopo.c

+15 −0
Original line number Diff line number Diff line
@@ -157,6 +157,21 @@ void cpu_topology__delete(struct cpu_topology *tp) 
	free(tp);

}



bool cpu_topology__smt_on(const struct cpu_topology *topology)

{

	for (u32 i = 0; i < topology->core_cpus_lists; i++) {

		const char *cpu_list = topology->core_cpus_list[i];



		/*

		 * If there is a need to separate siblings in a core then SMT is

		 * enabled.

		 */

		if (strchr(cpu_list, ',') || strchr(cpu_list, '-'))

			return true;

	}

	return false;

}



static bool has_die_topology(void)

{

	char filename[MAXPATHLEN];

tools/perf/util/cputopo.h

+2 −0
Original line number Diff line number Diff line
@@ -58,6 +58,8 @@ struct hybrid_topology { 


struct cpu_topology *cpu_topology__new(void);

void cpu_topology__delete(struct cpu_topology *tp);

/* Determine from the core list whether SMT was enabled. */

bool cpu_topology__smt_on(const struct cpu_topology *topology);



struct numa_topology *numa_topology__new(void);

void numa_topology__delete(struct numa_topology *tp);

tools/perf/util/expr.c

+4 −5
Original line number Diff line number Diff line
@@ -412,11 +412,6 @@ double expr__get_literal(const char *literal) 
	static struct cpu_topology *topology;

	double result = NAN;



	if (!strcasecmp("#smt_on", literal)) {

		result = smt_on() > 0 ? 1.0 : 0.0;

		goto out;

	}



	if (!strcmp("#num_cpus", literal)) {

		result = cpu__max_present_cpu().cpu;

		goto out;
@@ -440,6 +435,10 @@ double expr__get_literal(const char *literal) 
			goto out;

		}

	}

	if (!strcasecmp("#smt_on", literal)) {

		result = smt_on(topology) ? 1.0 : 0.0;

		goto out;

	}

	if (!strcmp("#num_packages", literal)) {

		result = topology->package_cpus_lists;

		goto out;

tools/perf/util/smt.c

+9 −86
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0-only

#include <stdio.h>

#include <stdlib.h>

#include <unistd.h>

#include <linux/bitops.h>

#include <string.h>

#include "api/fs/fs.h"

#include "cputopo.h"

#include "smt.h"



/**

 * hweight_str - Returns the number of bits set in str. Stops at first non-hex

 *	       or ',' character.

 */

static int hweight_str(char *str)

{

	int result = 0;



	while (*str) {

		switch (*str++) {

		case '0':

		case ',':

			break;

		case '1':

		case '2':

		case '4':

		case '8':

			result++;

			break;

		case '3':

		case '5':

		case '6':

		case '9':

		case 'a':

		case 'A':

		case 'c':

		case 'C':

			result += 2;

			break;

		case '7':

		case 'b':

		case 'B':

		case 'd':

		case 'D':

		case 'e':

		case 'E':

			result += 3;

			break;

		case 'f':

		case 'F':

			result += 4;

			break;

		default:

			goto done;

		}

	}

done:

	return result;

}



int smt_on(void)

bool smt_on(const struct cpu_topology *topology)

{

	static bool cached;

	static int cached_result;

	int cpu;

	int ncpu;

	static bool cached_result;

	int fs_value;



	if (cached)

		return cached_result;



	if (sysfs__read_int("devices/system/cpu/smt/active", &cached_result) >= 0) {

		cached = true;

		return cached_result;

	}



	cached_result = 0;

	ncpu = sysconf(_SC_NPROCESSORS_CONF);

	for (cpu = 0; cpu < ncpu; cpu++) {

		unsigned long long siblings;

		char *str;

		size_t strlen;

		char fn[256];

	if (sysfs__read_int("devices/system/cpu/smt/active", &fs_value) >= 0)

		cached_result = (fs_value == 1);

	else

		cached_result = cpu_topology__smt_on(topology);



		snprintf(fn, sizeof fn,

			"devices/system/cpu/cpu%d/topology/thread_siblings", cpu);

		if (sysfs__read_str(fn, &str, &strlen) < 0) {

			snprintf(fn, sizeof fn,

				"devices/system/cpu/cpu%d/topology/core_cpus", cpu);

			if (sysfs__read_str(fn, &str, &strlen) < 0)

				continue;

		}

		/* Entry is hex, but does not have 0x, so need custom parser */

		siblings = hweight_str(str);

		free(str);

		if (siblings > 1) {

			cached_result = 1;

			break;

		}

	}

	cached = true;

	return cached_result;

}