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178 changes: 178 additions & 0 deletions
178
eBPF_Supermarket/CPU_Subsystem/eBPF_proc_image/bpf/schedule_image.bpf.c
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| // Copyright 2023 The LMP Authors. | ||
| // | ||
| // Licensed 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 | ||
| // | ||
| // https://github.com/linuxkerneltravel/lmp/blob/develop/LICENSE | ||
| // | ||
| // 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. | ||
| // | ||
| // author: [email protected] | ||
| // | ||
| // eBPF kernel-mode code that collects process schedule information | ||
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| #include <vmlinux.h> | ||
| #include <bpf/bpf_helpers.h> | ||
| #include <bpf/bpf_core_read.h> | ||
| #include <bpf/bpf_tracing.h> | ||
| #include "proc_image.h" | ||
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| char LICENSE[] SEC("license") = "Dual BSD/GPL"; | ||
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| const volatile pid_t target_pid = -1; | ||
| const volatile int target_cpu_id = -1; | ||
| const volatile pid_t ignore_tgid = -1; | ||
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| struct { | ||
| __uint(type, BPF_MAP_TYPE_HASH); | ||
| __uint(max_entries, 10240); | ||
| __type(key, struct proc_id); | ||
| __type(value,struct schedule_event); | ||
| } proc_schedule SEC(".maps"); | ||
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| struct { | ||
| __uint(type, BPF_MAP_TYPE_HASH); | ||
| __uint(max_entries, 10240); | ||
| __type(key, struct proc_id); | ||
| __type(value,bool); | ||
| } enable_add SEC(".maps"); | ||
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| SEC("tp_btf/sched_wakeup") | ||
| int BPF_PROG(sched_wakeup, struct task_struct *p) | ||
| { | ||
| pid_t pid = BPF_CORE_READ(p,pid); | ||
| int tgid = BPF_CORE_READ(p,tgid); | ||
| int cpu = bpf_get_smp_processor_id(); | ||
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| if(tgid!=ignore_tgid && (target_pid==-1 || (target_pid!=0 && pid==target_pid) || | ||
| (target_pid==0 && pid==target_pid && cpu==target_cpu_id))){ | ||
| struct schedule_event *schedule_event; | ||
| struct proc_id pd = {}; | ||
| u64 current_time = bpf_ktime_get_ns(); | ||
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| pd.pid = pid; | ||
| if(pid == 0) pd.cpu_id = cpu; | ||
| schedule_event = bpf_map_lookup_elem(&proc_schedule,&pd); | ||
| if(!schedule_event){ | ||
| struct schedule_event schedule_event = {}; | ||
| bool e_add = false; | ||
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| schedule_event.pid = pid; | ||
| // 提前将 count 值赋值为 1，避免输出时进程还没有被调度，导致除数出现 0 的情况 | ||
| schedule_event.count = 1; | ||
| schedule_event.enter_time = current_time; | ||
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| bpf_map_update_elem(&enable_add,&pd,&e_add,BPF_ANY); | ||
| bpf_map_update_elem(&proc_schedule,&pd,&schedule_event,BPF_ANY); | ||
| }else{ | ||
| schedule_event->enter_time = current_time; | ||
| } | ||
| } | ||
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| return 0; | ||
| } | ||
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| SEC("tp_btf/sched_wakeup_new") | ||
| int BPF_PROG(sched_wakeup_new, struct task_struct *p) | ||
| { | ||
| pid_t pid = BPF_CORE_READ(p,pid); | ||
| int tgid = BPF_CORE_READ(p,tgid); | ||
| int cpu = bpf_get_smp_processor_id(); | ||
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| if(tgid!=ignore_tgid && (target_pid==-1 || (target_pid!=0 && pid==target_pid) || | ||
| (target_pid==0 && pid==target_pid && cpu==target_cpu_id))){ | ||
| struct schedule_event *schedule_event; | ||
| struct proc_id pd = {}; | ||
| u64 current_time = bpf_ktime_get_ns(); | ||
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| pd.pid = pid; | ||
| if(pid == 0) pd.cpu_id = cpu; | ||
| schedule_event = bpf_map_lookup_elem(&proc_schedule,&pd); | ||
| if(!schedule_event){ | ||
| struct schedule_event schedule_event = {}; | ||
| bool e_add = false; | ||
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| schedule_event.pid = pid; | ||
| schedule_event.count = 1; | ||
| schedule_event.enter_time = current_time; | ||
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| bpf_map_update_elem(&enable_add,&pd,&e_add,BPF_ANY); | ||
| bpf_map_update_elem(&proc_schedule,&pd,&schedule_event,BPF_ANY); | ||
| }else{ | ||
| schedule_event->enter_time = current_time; | ||
| } | ||
| } | ||
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| return 0; | ||
| } | ||
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| SEC("tp_btf/sched_switch") | ||
| int BPF_PROG(sched_switch, bool preempt, struct task_struct *prev, struct task_struct *next) | ||
| { | ||
| pid_t prev_pid = BPF_CORE_READ(prev,pid); | ||
| int prev_tgid = BPF_CORE_READ(prev,tgid); | ||
| int prev_cpu = bpf_get_smp_processor_id(); | ||
| unsigned int prev_state = BPF_CORE_READ(prev,__state); | ||
| pid_t next_pid = BPF_CORE_READ(next,pid); | ||
| int next_tgid = BPF_CORE_READ(next,tgid); | ||
| int next_cpu = prev_cpu; | ||
| u64 current_time = bpf_ktime_get_ns(); | ||
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| if(prev_tgid!=ignore_tgid && prev_state==TASK_RUNNING && (target_pid==-1 || (target_pid!=0 && prev_pid==target_pid) || | ||
| (target_pid==0 && prev_pid==target_pid && prev_cpu==target_cpu_id))){ | ||
| struct schedule_event *schedule_event; | ||
| struct proc_id pd = {}; | ||
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| pd.pid = prev_pid; | ||
| if(prev_pid == 0) pd.cpu_id = prev_cpu; | ||
| schedule_event = bpf_map_lookup_elem(&proc_schedule,&pd); | ||
| if(!schedule_event){ | ||
| struct schedule_event schedule_event = {}; | ||
| bool e_add = false; | ||
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| schedule_event.pid = prev_pid; | ||
| schedule_event.count = 1; | ||
| schedule_event.enter_time = current_time; | ||
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| bpf_map_update_elem(&enable_add,&pd,&e_add,BPF_ANY); | ||
| bpf_map_update_elem(&proc_schedule,&pd,&schedule_event,BPF_ANY); | ||
| }else{ | ||
| schedule_event->enter_time = current_time; | ||
| } | ||
| } | ||
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| if(next_tgid!=ignore_tgid && (target_pid==-1 || (target_pid!=0 && next_pid==target_pid) || | ||
| (target_pid==0 && next_pid==target_pid && next_cpu==target_cpu_id))){ | ||
| struct schedule_event *schedule_event; | ||
| bool * e_add; | ||
| struct proc_id pd = {}; | ||
| u64 this_delay; | ||
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| pd.pid = next_pid; | ||
| if(next_pid == 0) pd.cpu_id = next_cpu; | ||
| schedule_event = bpf_map_lookup_elem(&proc_schedule,&pd); | ||
| if(!schedule_event) | ||
| return 0; | ||
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| e_add = bpf_map_lookup_elem(&enable_add,&pd); | ||
| if(!e_add) return 0; | ||
| // 因为 count 值初值赋值为了 1，避免多加一次 | ||
| if(*e_add) schedule_event->count++; | ||
| else *e_add = true; | ||
| this_delay = current_time-schedule_event->enter_time; | ||
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| schedule_event->prio = BPF_CORE_READ(next,prio); | ||
| schedule_event->sum_delay += this_delay; | ||
| if(this_delay > schedule_event->max_delay) | ||
| schedule_event->max_delay = this_delay; | ||
| if(schedule_event->min_delay==0 || this_delay<schedule_event->min_delay) | ||
| schedule_event->min_delay = this_delay; | ||
| } | ||
|
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| return 0; | ||
| } |
31 changes: 31 additions & 0 deletions
31
eBPF_Supermarket/CPU_Subsystem/eBPF_proc_image/docs/schedule_develop.md
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| # schedule功能类开发文档 | ||
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| **参考资料：** | ||
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| - [Linux 的调度延迟 - 原理与观测 - 知乎 (zhihu.com)](https://zhuanlan.zhihu.com/p/462728452) | ||
| - [linux 内核抢占那些事 - 知乎 (zhihu.com)](https://zhuanlan.zhihu.com/p/166032722) | ||
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| **调度延迟的计算得分两种情况：** | ||
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| 1. 任务因等待 event 进入休眠态（[Voluntary Switch](https://zhuanlan.zhihu.com/p/402423877)），那么就是从被唤醒（"wakeup/wakeup_new" 的时间点），到获得 CPU （任务切换时的 *"next_pid"*）的间隔。 | ||
| 2. 任务因 [Involuntary Switch](https://zhuanlan.zhihu.com/p/402423877) 让出 CPU（任务切换时作为 *"prev_pid"*），到再次获得 CPU （之后的某次任务切换时作为*"next_pid"*）所经历的时间。在这期间，任务始终在 runqueue 上，始终是 runnable 的状态，所以有 "prev_state" 是否为 *TASK_RUNNING* 的判断。 | ||
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| **内核中提供了三个接口来唤醒进程：** | ||
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| - wake_up_new_task：用来唤醒新进程，fork出来的进程/线程； | ||
| - wake_up_process：唤醒处于TASK_NORMAL状态的进程； | ||
| - wake_up_state：唤醒指定状态的进程； | ||
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| 后两个接口最终都会调用try_to_wake_up接口： | ||
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| ``` | ||
| try_to_wake_up-->ttwu_queue-->ttwu_do_active-->ttwu_do_wakeup | ||
| ``` | ||
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| **相关挂载点：** | ||
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| ``` | ||
| ttwu_do_wakeup() --> trace_sched_wakeup | ||
| wake_up_new_task() --> trace_sched_wakeup_new | ||
| __schedule() --> trace_sched_switch | ||
| ``` |
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