我想使用ftrace来追踪一个固定进程的唤醒延迟时间。
但是,ftrace只会记录最大延迟时间。
而且,set_ftrace_pid是无用的。
有人知道该怎么做吗?
非常感谢。
有人知道该怎么做吗?
非常感谢。
除了 @Qeole 提供的建议外,您还可以使用 perf sched
实用程序来获取进程唤醒延迟的详细跟踪。虽然像 runqlat 这样的 ebpf
工具将为您提供更高级别的概述,但使用 perf sched
将帮助您捕获所有调度器事件,从而更详细地观察和检查进程的唤醒延迟。请注意,对于长时间运行的计算密集型进程运行 perf sched
会有自己的开销问题。
您首先需要运行 perf sched record
-
从 man-page 中,
'perf sched record <command>' records the scheduling events of an arbitrary workload.
ls
的唤醒延迟。sudo perf sched record ls
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 1.453 MB perf.data (562 samples) ]
在运行命令的同一目录下,您会看到生成了一个perf.data
文件。该文件将包含所有原始的调度事件,下面的命令将有助于理解所有这些调度事件。
perf sched latency
来获取每个任务的延迟摘要,包括每个任务的上下文切换次数、平均延迟和最大延迟等详细信息。sudo perf sched latency
-----------------------------------------------------------------------------------------------------------------
Task | Runtime ms | Switches | Average delay ms | Maximum delay ms | Maximum delay at |
-----------------------------------------------------------------------------------------------------------------
migration/4:35 | 0.000 ms | 1 | avg: 0.003 ms | max: 0.003 ms | max at: 231259.727951 s
kworker/u16:0-p:6962 | 0.103 ms | 20 | avg: 0.003 ms | max: 0.035 ms | max at: 231259.729314 s
ls:7118 | 1.752 ms | 1 | avg: 0.003 ms | max: 0.003 ms | max at: 231259.727898 s
alsa-sink-Gener:3133 | 0.000 ms | 1 | avg: 0.003 ms | max: 0.003 ms | max at: 231259.729321 s
Timer:5229 | 0.035 ms | 1 | avg: 0.002 ms | max: 0.002 ms | max at: 231259.729625 s
AudioIP~ent RPC:7597 | 0.040 ms | 1 | avg: 0.002 ms | max: 0.002 ms | max at: 231259.729698 s
MediaTimer #1:7075 | 0.025 ms | 1 | avg: 0.002 ms | max: 0.002 ms | max at: 231259.729651 s
gnome-terminal-:4989 | 0.254 ms | 24 | avg: 0.001 ms | max: 0.003 ms | max at: 231259.729358 s
MediaPl~back #3:7098 | 0.034 ms | 1 | avg: 0.001 ms | max: 0.001 ms | max at: 231259.729670 s
kworker/u16:2-p:5987 | 0.144 ms | 32 | avg: 0.001 ms | max: 0.002 ms | max at: 231259.729193 s
perf:7114 | 3.503 ms | 1 | avg: 0.001 ms | max: 0.001 ms | max at: 231259.729656 s
kworker/u16:1-p:7112 | 0.184 ms | 52 | avg: 0.001 ms | max: 0.001 ms | max at: 231259.729201 s
chrome:5713 | 0.067 ms | 1 | avg: 0.000 ms | max: 0.000 ms | max at: 0.000000 s
-----------------------------------------------------------------------------------------------------------------
TOTAL: | 6.141 ms | 137 |
---------------------------------------------------
在运行perf sched record
命令时,您可以看到进程ls
和进程perf
与其他共存的进程一起存在。
perf sched timehist
来获取有关单个调度事件的详细摘要。sudo perf sched timehist
time cpu task name wait time sch delay run time
[tid/pid] (msec) (msec) (msec)
--------------- ------ ------------------------------ --------- --------- ---------
231259.726350 [0005] <idle> 0.000 0.000 0.000
231259.726465 [0005] chrome[5713] 0.000 0.000 0.114
231259.727447 [0005] <idle> 0.114 0.000 0.981
231259.727513 [0005] chrome[5713] 0.981 0.000 0.066
231259.727898 [0004] <idle> 0.000 0.000 0.000
231259.727951 [0004] perf[7118] 0.000 0.002 0.052
231259.727958 [0002] perf[7114] 0.000 0.000 0.000
231259.727960 [0000] <idle> 0.000 0.000 0.000
231259.727964 [0004] migration/4[35] 0.000 0.002 0.013
231259.729193 [0006] <idle> 0.000 0.000 0.000
231259.729201 [0002] <idle> 0.000 0.000 1.242
231259.729201 [0003] <idle> 0.000 0.000 0.000 231259.729216 [0002] kworker/u16:1-p[7112] 0.006 0.001 0.005
231259.729219 [0002] <idle> 0.005 0.000 0.002
231259.729222 [0002] kworker/u16:1-p[7112] 0.002 0.000 0.002
231259.729222 [0006] <idle> 0.001 0.000 0.007
等待时间
指的是任务等待被唤醒的时间,而调度延迟
则是调度器在任务被唤醒后实际将其调度到运行队列中所需的时间。
您可以通过pid
过滤timehist
命令,而由于ls
命令的pid
为7118(您可以在perf sched latency
输出中观察到此)。
sudo perf sched timehist -p 7118
Samples do not have callchains.
time cpu task name wait time sch delay run time
[tid/pid] (msec) (msec) (msec)
--------------- ------ ------------------------------ --------- --------- ---------
231259.727951 [0004] perf[7118] 0.000 0.002 0.052
231259.729657 [0000] ls[7118] 0.009 0.000 1.697
现在,为了观测该进程的唤醒事件,你可以在之前的命令中添加一个命令行开关-w
-
sudo perf sched timehist -p 7118 -w
Samples do not have callchains.
time cpu task name wait time sch delay run time
[tid/pid] (msec) (msec) (msec)
--------------- ------ ------------------------------ --------- --------- ---------
231259.727895 [0002] perf[7114] awakened: perf[7118]
231259.727948 [0004] perf[7118] awakened: migration/4[35]
231259.727951 [0004] perf[7118] 0.000 0.002 0.052
231259.729190 [0000] ls[7118] awakened: kworker/u16:2-p[5987]
231259.729199 [0000] ls[7118] awakened: kworker/u16:1-p[7112]
231259.729207 [0000] ls[7118] awakened: kworker/u16:2-p[5987]
231259.729209 [0000] ls[7118] awakened: kworker/u16:1-p[7112]
231259.729212 [0000] ls[7118] awakened: kworker/u16:2-p[5987]
231259.729218 [0000] ls[7118] awakened: kworker/u16:1-p[7112]
231259.729221 [0000] ls[7118] awakened: kworker/u16:2-p[5987]
231259.729223 [0000] ls[7118] awakened: kworker/u16:1-p[7112]
231259.729226 [0000] ls[7118] awakened: kworker/u16:1-p[7112]
231259.729231 [0000] ls[7118] awakened: kworker/u16:1-p[7112]
231259.729233 [0000] ls[7118] awakened: kworker/u16:2-p[5987]
231259.729237 [0000] ls[7118] awakened: kworker/u16:2-p[5987]
231259.729240 [0000] ls[7118] awakened: kworker/u16:1-p[7112]
231259.729242 [0000] ls[7118] awakened: kworker/u16:2-p[5987]
-------------------------------------- # some other events here
231259.729548 [0000] ls[7118] awakened: kworker/u16:0-p[6962]
231259.729553 [0000] ls[7118] awakened: kworker/u16:1-p[7112]
231259.729555 [0000] ls[7118] awakened: kworker/u16:0-p[6962]
231259.729557 [0000] ls[7118] awakened: kworker/u16:1-p[7112]
231259.729562 [0000] ls[7118] awakened: kworker/u16:0-p[6962]
231259.729564 [0000] ls[7118] awakened: kworker/u16:1-p[7112]
231259.729655 [0000] ls[7118] awakened: perf[7114]
231259.729657 [0000] ls[7118] 0.009 0.000 1.697
kworker
线程在231259.729190毫秒时打断了perf
及其子进程ls
的初始执行。您可以看到,在所有内核工作线程完成一些工作后,perf
进程最终会被唤醒并在231259.729655毫秒时实际执行。您可以使用以下命令获得有关上述timehist
详细信息的更详细的CPU可视化:
sudo perf sched timehist -p 7118 -wV
Samples do not have callchains.
time cpu 012345678 task name wait time sch delay run time
[tid/pid] (msec) (msec) (msec)
--------------- ------ --------- ------------------------------ --------- --------- ---------
231259.727895 [0002] perf[7114] awakened: perf[7118]
231259.727948 [0004] perf[7118] awakened: migration/4[35]
231259.727951 [0004] s perf[7118] 0.000 0.002 0.052
231259.729190 [0000] ls[7118] awakened: kworker/u16:2-p[5987]
231259.729199 [0000] ls[7118] awakened: kworker/u16:1-p[7112]
231259.729207 [0000] ls[7118] awakened: kworker/u16:2-p[5987]
231259.729209 [0000] ls[7118] awakened: kworker/u16:1-p[7112]
231259.729212 [0000] ls[7118] awakened: kworker/u16:2-p[5987]
-------------------------------------------------- # some other events here
231259.729562 [0000] ls[7118] awakened: kworker/u16:0-p[6962]
231259.729564 [0000] ls[7118] awakened: kworker/u16:1-p[7112]
231259.729655 [0000] ls[7118] awakened: perf[7114]
231259.729657 [0000] s ls[7118] 0.009 0.000 1.697
perf sched
的其余命令输出来补充上述信息,即perf sched script
和perf sched map
。