1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
|
// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES
*/
#include <scx/common.bpf.h>
#include "kick_test.h"
char _license[] SEC("license") = "GPL";
const volatile u32 scenario;
const volatile s32 victim_pid;
const volatile s32 challenger_pid;
const volatile s32 target_cpu;
const volatile s32 lazy_resched_override = -1;
u32 state;
u64 slice_before;
u64 slice_at_resched;
s32 resched_tif;
u64 nr_wait_callbacks;
bool enq_preempt_issued;
UEI_DEFINE(uei);
static bool is_trace_scenario(void)
{
return scenario <= TICK_EXPIRY;
}
void BPF_STRUCT_OPS(kick_enqueue, struct task_struct *p, u64 enq_flags)
{
switch (scenario) {
case ENQ_BOTH:
if (p->pid == victim_pid) {
scx_bpf_dsq_insert(p, SCX_DSQ_GLOBAL, SCX_SLICE_INF, enq_flags);
} else if (p->pid == challenger_pid && state == KICK_STATE_QUEUED) {
enq_preempt_issued = true;
scx_bpf_dsq_insert(p, SCX_DSQ_LOCAL, SCX_SLICE_DFL,
enq_flags | SCX_ENQ_PREEMPT |
SCX_ENQ_PREEMPT_LAZY);
} else {
scx_bpf_dsq_insert(p, SCX_DSQ_GLOBAL, SCX_SLICE_DFL, enq_flags);
}
goto kick_last;
case INVALID_KICK_IDLE:
scx_bpf_kick_cpu(scx_bpf_task_cpu(p), SCX_KICK_PREEMPT_LAZY | SCX_KICK_IDLE);
break;
case INVALID_KICK_UNKNOWN:
scx_bpf_kick_cpu(scx_bpf_task_cpu(p), 1LLU << 63);
break;
}
scx_bpf_dsq_insert(p, SCX_DSQ_GLOBAL, SCX_SLICE_DFL, enq_flags);
kick_last:
if (enq_flags & SCX_ENQ_LAST)
scx_bpf_kick_cpu(target_cpu, SCX_KICK_IDLE);
}
static void set_lazy_resched_override(struct task_struct *p)
{
if (p->pid == victim_pid && lazy_resched_override >= 0)
scx_bpf_task_set_lazy_resched(p, lazy_resched_override);
}
void BPF_STRUCT_OPS(kick_running, struct task_struct *p)
{
if (!is_trace_scenario() || p->pid != victim_pid)
return;
set_lazy_resched_override(p);
if (__sync_val_compare_and_swap(&state, KICK_STATE_ARMED, KICK_STATE_QUEUED) !=
KICK_STATE_ARMED)
return;
slice_before = p->scx.slice;
switch (scenario) {
case KICK_IMMEDIATE:
scx_bpf_kick_cpu(target_cpu, SCX_KICK_PREEMPT);
break;
case KICK_LAZY:
scx_bpf_kick_cpu(target_cpu, SCX_KICK_PREEMPT_LAZY);
break;
case KICK_LAZY_THEN_IMMEDIATE:
scx_bpf_kick_cpu(target_cpu, SCX_KICK_PREEMPT_LAZY);
scx_bpf_kick_cpu(target_cpu, SCX_KICK_PREEMPT);
break;
case KICK_IMMEDIATE_THEN_LAZY:
scx_bpf_kick_cpu(target_cpu, SCX_KICK_PREEMPT);
scx_bpf_kick_cpu(target_cpu, SCX_KICK_PREEMPT_LAZY);
break;
case KICK_PLAIN_THEN_LAZY:
scx_bpf_kick_cpu(target_cpu, 0);
scx_bpf_kick_cpu(target_cpu, SCX_KICK_PREEMPT_LAZY);
break;
case KICK_LAZY_THEN_PLAIN:
scx_bpf_kick_cpu(target_cpu, SCX_KICK_PREEMPT_LAZY);
scx_bpf_kick_cpu(target_cpu, 0);
break;
case KICK_BOTH:
scx_bpf_kick_cpu(target_cpu, SCX_KICK_PREEMPT | SCX_KICK_PREEMPT_LAZY);
break;
case KICK_LAZY_WAIT:
scx_bpf_kick_cpu(target_cpu, SCX_KICK_PREEMPT_LAZY | SCX_KICK_WAIT);
break;
case ENQ_BOTH:
/* The userspace controller wakes a competing task. */
break;
case TICK_EXPIRY:
/* no kick: the slice runs out at the tick */
break;
}
}
SEC("fexit/__resched_curr")
int BPF_PROG(kick_need_resched, struct rq *rq, int tif)
{
struct task_struct *task = BPF_CORE_READ(rq, curr);
u64 slice;
if (!task || BPF_CORE_READ(task, pid) != victim_pid ||
BPF_CORE_READ(rq, cpu) != target_cpu || state != KICK_STATE_QUEUED)
return 0;
if (scenario == ENQ_BOTH && !enq_preempt_issued)
return 0;
slice = BPF_CORE_READ(task, scx.slice);
if (slice)
return 0;
slice_at_resched = slice;
resched_tif = tif;
state = KICK_STATE_RESCHED;
return 0;
}
SEC("fentry/kick_sync_wait_bal_cb")
int BPF_PROG(kick_wait_callback, struct rq *rq)
{
if (scenario == KICK_LAZY_WAIT && BPF_CORE_READ(rq, cpu) == target_cpu)
__sync_fetch_and_add(&nr_wait_callbacks, 1);
return 0;
}
void BPF_STRUCT_OPS(kick_stopping, struct task_struct *p, bool runnable)
{
if (p->pid == victim_pid && state == KICK_STATE_RESCHED)
state = KICK_STATE_DONE;
}
void BPF_STRUCT_OPS(kick_exit, struct scx_exit_info *ei)
{
UEI_RECORD(uei, ei);
}
SEC(".struct_ops.link")
struct sched_ext_ops kick_ops = {
.enqueue = (void *)kick_enqueue,
.running = (void *)kick_running,
.stopping = (void *)kick_stopping,
.exit = (void *)kick_exit,
.flags = SCX_OPS_ENQ_LAST,
.name = "kick",
};
|
