tools/testing/selftests/sched_ext/select_cpu_vtime.bpf.c

Source file repositories/reference/linux-study-clean/tools/testing/selftests/sched_ext/select_cpu_vtime.bpf.c

File Facts

System
Linux kernel
Corpus path
tools/testing/selftests/sched_ext/select_cpu_vtime.bpf.c
Extension
.c
Size
2417 bytes
Lines
95
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

#include <scx/common.bpf.h>

char _license[] SEC("license") = "GPL";

volatile bool consumed;

static u64 vtime_now;

#define VTIME_DSQ 0

static inline bool vtime_before(u64 a, u64 b)
{
	return (s64)(a - b) < 0;
}

static inline u64 task_vtime(const struct task_struct *p)
{
	u64 vtime = p->scx.dsq_vtime;

	if (vtime_before(vtime, vtime_now - SCX_SLICE_DFL))
		return vtime_now - SCX_SLICE_DFL;
	else
		return vtime;
}

s32 BPF_STRUCT_OPS(select_cpu_vtime_select_cpu, struct task_struct *p,
		   s32 prev_cpu, u64 wake_flags)
{
	s32 cpu;

	cpu = scx_bpf_pick_idle_cpu(p->cpus_ptr, 0);
	if (cpu >= 0)
		goto ddsp;

	cpu = prev_cpu;
	scx_bpf_test_and_clear_cpu_idle(cpu);
ddsp:
	scx_bpf_dsq_insert_vtime(p, VTIME_DSQ, SCX_SLICE_DFL, task_vtime(p), 0);
	return cpu;
}

void BPF_STRUCT_OPS(select_cpu_vtime_dispatch, s32 cpu, struct task_struct *p)
{
	if (scx_bpf_dsq_move_to_local(VTIME_DSQ, 0))
		consumed = true;
}

void BPF_STRUCT_OPS(select_cpu_vtime_running, struct task_struct *p)
{
	if (vtime_before(vtime_now, p->scx.dsq_vtime))
		vtime_now = p->scx.dsq_vtime;
}

void BPF_STRUCT_OPS(select_cpu_vtime_stopping, struct task_struct *p,
		    bool runnable)
{
	u64 delta = scale_by_task_weight_inverse(p, SCX_SLICE_DFL - p->scx.slice);

	scx_bpf_task_set_dsq_vtime(p, p->scx.dsq_vtime + delta);
}

void BPF_STRUCT_OPS(select_cpu_vtime_enable, struct task_struct *p)
{
	scx_bpf_task_set_dsq_vtime(p, vtime_now);
}

s32 BPF_STRUCT_OPS_SLEEPABLE(select_cpu_vtime_init)
{
	return scx_bpf_create_dsq(VTIME_DSQ, -1);
}

SEC(".struct_ops.link")
struct sched_ext_ops select_cpu_vtime_ops = {
	.select_cpu		= (void *) select_cpu_vtime_select_cpu,
	.dispatch		= (void *) select_cpu_vtime_dispatch,
	.running		= (void *) select_cpu_vtime_running,
	.stopping		= (void *) select_cpu_vtime_stopping,
	.enable			= (void *) select_cpu_vtime_enable,
	.init			= (void *) select_cpu_vtime_init,
	.name			= "select_cpu_vtime",
	.timeout_ms		= 1000U,
};

Annotation

Implementation Notes