* NO_HZ and cpu monitoring tools
@ 2007-10-14 23:42 Anton Blanchard
0 siblings, 0 replies; only message in thread
From: Anton Blanchard @ 2007-10-14 23:42 UTC (permalink / raw)
To: mingo, tglx; +Cc: linux-kernel
Hi,
When using a NO_HZ kernel on ppc64, I noticed top gives some interesting
results:
Cpu0 : 0.0%us, 0.0%sy, 0.0%ni,100.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu1 : 0.0%us, 0.0%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu2 : 0.0%us, 0.0%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu3 : 0.0%us, 0.0%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu4 : 0.0%us, 0.0%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu5 : 1.1%us, 0.0%sy, 0.0%ni, 98.9%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu6 : 0.0%us, 0.0%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu7 : 0.0%us, 0.0%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Notice how only 2 cpus report idle time. Im guessing this happens if
a core sleeps for longer than the update period in top. Where should
this be fixed?
It would be possible for the proc read method to add in the right number
of idle jiffies, or top could just assume no increment means 100% idle.
Anton
^ permalink raw reply [flat|nested] only message in thread
only message in thread, other threads:[~2007-10-14 23:46 UTC | newest]
Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2007-10-14 23:42 NO_HZ and cpu monitoring tools Anton Blanchard
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®