tools/perf/util/bpf_skel/off_cpu.bpf.c

File Facts

System

Linux kernel

Corpus path

tools/perf/util/bpf_skel/off_cpu.bpf.c

Extension

.c

Size

8643 bytes

Lines

373

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.

• Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.
• Defines or uses C structs; map object ownership, embedded links, reference counts, and lock ownership.

Dependency Surface

• vmlinux.h
• bpf/bpf_helpers.h
• bpf/bpf_tracing.h
• bpf/bpf_core_read.h

Detected Declarations

• struct __stack
• struct tstamp_data
• struct offcpu_key
• struct offcpu_data
• struct task_struct___new
• struct task_struct___old
• function get_task_state
• function get_cgroup_id
• function can_record
• function copy_stack
• function off_cpu_dump
• function off_cpu_stat
• function bpf_get_stackid
• function on_newtask
• function on_switch

Annotated Snippet

struct __stack {
	u64 array[MAX_STACKS];
};

struct tstamp_data {
	__u32 stack_id;
	__u32 state;
	__u64 timestamp;
	struct __stack stack;
};

struct offcpu_key {
	__u32 pid;
	__u32 tgid;
	__u32 stack_id;
	__u32 state;
	__u64 cgroup_id;
};

struct {
	__uint(type, BPF_MAP_TYPE_STACK_TRACE);
	__uint(key_size, sizeof(__u32));
	__uint(value_size, MAX_STACKS * sizeof(__u64));
	__uint(max_entries, MAX_ENTRIES);
} stacks SEC(".maps");

struct offcpu_data {
	u64 array[MAX_OFFCPU_LEN];
};

struct {
	__uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
	__uint(key_size, sizeof(int));
	__uint(value_size, sizeof(int));
	__uint(max_entries, MAX_CPUS);
} offcpu_output SEC(".maps");

struct {
	__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
	__uint(key_size, sizeof(__u32));
	__uint(value_size, sizeof(struct offcpu_data));
	__uint(max_entries, 1);
} offcpu_payload SEC(".maps");

struct {
	__uint(type, BPF_MAP_TYPE_TASK_STORAGE);
	__uint(map_flags, BPF_F_NO_PREALLOC);
	__type(key, int);
	__type(value, struct tstamp_data);
} tstamp SEC(".maps");

struct {
	__uint(type, BPF_MAP_TYPE_HASH);
	__uint(key_size, sizeof(struct offcpu_key));
	__uint(value_size, sizeof(__u64));
	__uint(max_entries, MAX_ENTRIES);
} off_cpu SEC(".maps");

struct {
	__uint(type, BPF_MAP_TYPE_HASH);
	__uint(key_size, sizeof(__u32));
	__uint(value_size, sizeof(__u8));
	__uint(max_entries, 1);
} cpu_filter SEC(".maps");

struct {
	__uint(type, BPF_MAP_TYPE_HASH);
	__uint(key_size, sizeof(__u32));
	__uint(value_size, sizeof(__u8));
	__uint(max_entries, 1);
} task_filter SEC(".maps");

struct {
	__uint(type, BPF_MAP_TYPE_HASH);
	__uint(key_size, sizeof(__u64));
	__uint(value_size, sizeof(__u8));
	__uint(max_entries, 1);
} cgroup_filter SEC(".maps");

/* new kernel task_struct definition */
struct task_struct___new {
	long __state;
} __attribute__((preserve_access_index));

/* old kernel task_struct definition */
struct task_struct___old {
	long state;
} __attribute__((preserve_access_index));

int enabled = 0;

Annotation

• Immediate include surface: `vmlinux.h`, `bpf/bpf_helpers.h`, `bpf/bpf_tracing.h`, `bpf/bpf_core_read.h`.
• Detected declarations: `struct __stack`, `struct tstamp_data`, `struct offcpu_key`, `struct offcpu_data`, `struct task_struct___new`, `struct task_struct___old`, `function get_task_state`, `function get_cgroup_id`, `function can_record`, `function copy_stack`.
• Atlas domain: Support Tooling And Documentation / tools.
• Implementation status: source implementation candidate.

Implementation Notes

• This generated page is the file-by-file coverage layer; curated subsystem chapters should link here when they synthesize a multi-file control flow.
• Core OS pages should be promoted from atlas-only to deep-reviewed when they explain data structures, invariants, locking, lifecycle, and C implementation snippets.
• Driver-family pages are intentionally pattern-oriented unless they are part of the selected PCIe/NVMe representative device path.