This is part 2 of
"Proper kernel irq time accounting -v4"
http://lkml.indiana.edu/hypermail//linux/kernel/1010.0/01175.html
and applies over those changes.
Part 1 solves the way irqs are accounted in scheduler and tasks. This
patchset solves how irq times are reported in /proc/stat and also not
to include irq time in task->stime, etc.
Example:
Running a cpu intensive loop and network intensive nc on a 4 CPU system
and looking at 'top' output.
With vanilla kernel:
Cpu0 : 0.0% us, 0.3% sy, 0.0% ni, 99.3% id, 0.0% wa, 0.0% hi, 0.3% si
Cpu1 : 100.0% us, 0.0% sy, 0.0% ni, 0.0% id, 0.0% wa, 0.0% hi, 0.0% si
Cpu2 : 1.3% us, 27.2% sy, 0.0% ni, 0.0% id, 0.0% wa, 0.0% hi, 71.4% si
Cpu3 : 1.6% us, 1.3% sy, 0.0% ni, 96.7% id, 0.0% wa, 0.0% hi, 0.3% si
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
7555 root 20 0 1760 528 436 R 100 0.0 0:15.79 nc
7563 root 20 0 3632 268 204 R 100 0.0 0:13.13 loop
Notes:
- Both tasks show 100% CPU, even when one of them is stuck on a CPU thats
processing 70% softirq.
- no hardirq time.
With "part 1" patches:
Cpu0 : 0.0% us, 0.0% sy, 0.0% ni, 100.0% id, 0.0% wa, 0.0% hi, 0.0% si
Cpu1 : 100.0% us, 0.0% sy, 0.0% ni, 0.0% id, 0.0% wa, 0.0% hi, 0.0% si
Cpu2 : 2.0% us, 30.6% sy, 0.0% ni, 0.0% id, 0.0% wa, 0.0% hi, 67.4% si
Cpu3 : 0.7% us, 0.7% sy, 0.3% ni, 98.3% id, 0.0% wa, 0.0% hi, 0.0% si
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
6289 root 20 0 3632 268 204 R 100 0.0 2:18.67 loop
5737 root 20 0 1760 528 436 R 33 0.0 0:26.72 nc
Notes:
- Tasks show 100% CPU and 33% CPU that correspond to their non-irq exec time.
- no hardirq time.
With "part 1 + part 2" patches:
Cpu0 : 1.3% us, 1.0% sy, 0.3% ni, 97.0% id, 0.0% wa, 0.0% hi, 0.3% si
Cpu1 : 99.3% us, 0.0% sy, 0.0% ni, 0.0% id, 0.0% wa, 0.7% hi, 0.0% si
Cpu2 : 1.3% us, 31.5% sy, 0.0% ni, 0.0% id, 0.0% wa, 8.3% hi, 58.9% si
Cpu3 : 1.0% us, 2.0% sy, 0.3% ni, 95.0% id, 0.0% wa, 0.7% hi, 1.0% si
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
20929 root 20 0 3632 268 204 R 99 0.0 3:48.25 loop
20796 root 20 0 1760 528 436 R 33 0.0 2:38.65 nc
Notes:
- Both task exec time and hard irq time reported correctly.
- hi and si time are based on fine granularity info and not on samples.
- getrusage would give proper utime/stime split not including irq times
in that ratio.
- Other places that report user/sys time like, cgroup cpuacct.stat will
now include only non-irq exectime.
Thanks,
Venki
Signed-off-by: Venkatesh Pallipadi <venki@google.com>
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