tools/perf/util/smt.c

Source file repositories/reference/linux-study-clean/tools/perf/util/smt.c

File Facts

System
Linux kernel
Corpus path
tools/perf/util/smt.c
Extension
.c
Size
850 bytes
Lines
37
Domain
Support Tooling And Documentation
Bucket
tools
Inferred role
Support Tooling And Documentation: implementation source
Status
source implementation candidate

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0-only
#include <string.h>
#include "api/fs/fs.h"
#include "cputopo.h"
#include "smt.h"

bool smt_on(void)
{
	static bool cached;
	static bool cached_result;
	int fs_value;

	if (cached)
		return cached_result;

	if (sysfs__read_int("devices/system/cpu/smt/active", &fs_value) >= 0)
		cached_result = (fs_value == 1);
	else
		cached_result = cpu_topology__smt_on(online_topology());

	cached = true;
	return cached_result;
}

bool core_wide(bool system_wide, const char *user_requested_cpu_list)
{
	/* If not everything running on a core is being recorded then we can't use core_wide. */
	if (!system_wide)
		return false;

	/* Cheap case that SMT is disabled and therefore we're inherently core_wide. */
	if (!smt_on())
		return true;

	return cpu_topology__core_wide(online_topology(), user_requested_cpu_list);
}

Annotation

Implementation Notes