[Bug 30557] Re: cpu idle time in /proc/stat wrong

[João Manuel Rodrigues]

I'm now running linux-image-2.6.15-26-686, version 2.6.15-26.46 on a
Pentium M 740 1.73MHz (Acer Aspire 1692WLMi).

So far, it seems fine: Without changing max_cstate, CPU rapidly throtles
down to 800MHz and, when idle, CPU usage settles around 5--6%.  Starting
new apps, such as opening a firefox window, does not feel sluggish like
it used to.

Here is a sample of data taken some 19 minutes after booting, laptop
connected to AC power, with Wi-Fi on and a USB mouse plugged in:

$ cat /sys/module/processor/parameters/max_cstate
8

$ top

top - 18:56:55 up 14 min,  3 users,  load average: 0.08, 0.33, 0.27
Tasks: 103 total,   1 running, 102 sleeping,   0 stopped,   0 zombie
Cpu(s):  5.3% us,  0.0% sy,  0.0% ni, 94.7% id,  0.0% wa,  0.0% hi,  0.0% si
...

$ cat /proc/acpi/processor/CPU*/power
active state:            C2
max_cstate:              C8
bus master activity:     04004002
states:
    C1:                  type[C1] promotion[C2] demotion[--] latency[000] usage[00000010]
   *C2:                  type[C2] promotion[C3] demotion[C1] latency[001] usage[00356747]
    C3:                  type[C3] promotion[C4] demotion[C2] latency[085] usage[00053269]
    C4:                  type[C3] promotion[--] demotion[C3] latency[185] usage[00065042]


Looks like this one is fixed.  Thanks.

-- 
cpu idle time in /proc/stat wrong
https://launchpad.net/bugs/30557