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-rw-r--r--tools/bpf/runqslower/runqslower.bpf.c107
1 files changed, 107 insertions, 0 deletions
diff --git a/tools/bpf/runqslower/runqslower.bpf.c b/tools/bpf/runqslower/runqslower.bpf.c
new file mode 100644
index 000000000..9a5c1f008
--- /dev/null
+++ b/tools/bpf/runqslower/runqslower.bpf.c
@@ -0,0 +1,107 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2019 Facebook
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include "runqslower.h"
+
+#define TASK_RUNNING 0
+#define BPF_F_CURRENT_CPU 0xffffffffULL
+
+const volatile __u64 min_us = 0;
+const volatile pid_t targ_pid = 0;
+
+struct {
+ __uint(type, BPF_MAP_TYPE_TASK_STORAGE);
+ __uint(map_flags, BPF_F_NO_PREALLOC);
+ __type(key, int);
+ __type(value, u64);
+} start SEC(".maps");
+
+struct {
+ __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
+ __uint(key_size, sizeof(u32));
+ __uint(value_size, sizeof(u32));
+} events SEC(".maps");
+
+/* record enqueue timestamp */
+__always_inline
+static int trace_enqueue(struct task_struct *t)
+{
+ u32 pid = t->pid;
+ u64 *ptr;
+
+ if (!pid || (targ_pid && targ_pid != pid))
+ return 0;
+
+ ptr = bpf_task_storage_get(&start, t, 0,
+ BPF_LOCAL_STORAGE_GET_F_CREATE);
+ if (!ptr)
+ return 0;
+
+ *ptr = bpf_ktime_get_ns();
+ return 0;
+}
+
+SEC("tp_btf/sched_wakeup")
+int handle__sched_wakeup(u64 *ctx)
+{
+ /* TP_PROTO(struct task_struct *p) */
+ struct task_struct *p = (void *)ctx[0];
+
+ return trace_enqueue(p);
+}
+
+SEC("tp_btf/sched_wakeup_new")
+int handle__sched_wakeup_new(u64 *ctx)
+{
+ /* TP_PROTO(struct task_struct *p) */
+ struct task_struct *p = (void *)ctx[0];
+
+ return trace_enqueue(p);
+}
+
+SEC("tp_btf/sched_switch")
+int handle__sched_switch(u64 *ctx)
+{
+ /* TP_PROTO(bool preempt, struct task_struct *prev,
+ * struct task_struct *next)
+ */
+ struct task_struct *prev = (struct task_struct *)ctx[1];
+ struct task_struct *next = (struct task_struct *)ctx[2];
+ struct runq_event event = {};
+ u64 *tsp, delta_us;
+ long state;
+ u32 pid;
+
+ /* ivcsw: treat like an enqueue event and store timestamp */
+ if (prev->__state == TASK_RUNNING)
+ trace_enqueue(prev);
+
+ pid = next->pid;
+
+ /* For pid mismatch, save a bpf_task_storage_get */
+ if (!pid || (targ_pid && targ_pid != pid))
+ return 0;
+
+ /* fetch timestamp and calculate delta */
+ tsp = bpf_task_storage_get(&start, next, 0, 0);
+ if (!tsp)
+ return 0; /* missed enqueue */
+
+ delta_us = (bpf_ktime_get_ns() - *tsp) / 1000;
+ if (min_us && delta_us <= min_us)
+ return 0;
+
+ event.pid = pid;
+ event.delta_us = delta_us;
+ bpf_get_current_comm(&event.task, sizeof(event.task));
+
+ /* output */
+ bpf_perf_event_output(ctx, &events, BPF_F_CURRENT_CPU,
+ &event, sizeof(event));
+
+ bpf_task_storage_delete(&start, next);
+ return 0;
+}
+
+char LICENSE[] SEC("license") = "GPL";