| // Licensed to Apache Software Foundation (ASF) under one or more contributor |
| // license agreements. See the NOTICE file distributed with |
| // this work for additional information regarding copyright |
| // ownership. Apache Software Foundation (ASF) licenses this file to you under |
| // the Apache License, Version 2.0 (the "License"); you may |
| // not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, |
| // software distributed under the License is distributed on an |
| // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| // KIND, either express or implied. See the License for the |
| // specific language governing permissions and limitations |
| // under the License. |
| |
| #include "api.h" |
| #include "offcpu.h" |
| |
| char __license[] SEC("license") = "Dual MIT/GPL"; |
| |
| SEC("kprobe/finish_task_switch") |
| int do_finish_task_switch(struct pt_regs *ctx) { |
| int monitor_pid; |
| asm("%0 = MONITOR_PID ll" : "=r"(monitor_pid)); |
| |
| __u32 pid, tgid; |
| __u64 ts, *tsp; |
| |
| struct task_struct *prev = (void *) PT_REGS_PARM1(ctx); |
| pid = _KERNEL(prev->pid); |
| tgid = _KERNEL(prev->tgid); |
| |
| // in kernel, tgid means the process id |
| // monitor_pid is the same concept with process id |
| // only the monitor pid is same with previous process id could record the start time |
| if (tgid == monitor_pid) { |
| ts = bpf_ktime_get_ns(); |
| bpf_map_update_elem(&starts, &pid, &ts, BPF_ANY); |
| } |
| |
| // if current process have record start time in the map |
| // means the monitored process switch to the on-cpu |
| struct task_struct *current = (void *)bpf_get_current_task(); |
| pid = _(current->pid); |
| tgid = _(current->tgid); |
| if (tgid != monitor_pid) { |
| return 0; |
| } |
| tsp = bpf_map_lookup_elem(&starts, &pid); |
| if (tsp == 0) { |
| return 0; // missed start or filtered |
| } |
| |
| // calculate the duration(on->off to off->on) |
| __u64 t_start = *tsp; |
| __u64 t_end = bpf_ktime_get_ns(); |
| bpf_map_delete_elem(&starts, &pid); |
| if (t_start > t_end) { |
| return 0; |
| } |
| |
| // create map key |
| struct key_t key = {}; |
| key.kernel_stack_id = bpf_get_stackid(ctx, &stacks, 0); |
| key.user_stack_id = bpf_get_stackid(ctx, &stacks, (1ULL << 8)); |
| |
| // add counters |
| struct value_t *val; |
| val = bpf_map_lookup_elem(&counts, &key); |
| if (!val) { |
| struct value_t value = {}; |
| bpf_map_update_elem(&counts, &key, &value, BPF_NOEXIST); |
| val = bpf_map_lookup_elem(&counts, &key); |
| if (!val) |
| return 0; |
| } |
| (*val).counts += 1; |
| (*val).deltas += t_end - t_start; |
| return 0; |
| } |