highres timers break cpu hotplug in 2.6.23-rc5 [was Re: cpu hotplug support broken in 2.6.23-rc3]

[Pavel Machek <pavel@ucw.cz>]

Hi!

> > Can you try 20-or-so tests? Mine hangs randomly, so it survived 4 or
> > so cycles at one point.
> 
> Mine still survives with this ... with sleep 1 ...
> 
> # for((i=0; i<100; i++)); do echo $i; echo $((i % 2))
> >/sys/devices/system/cpu/cpu1/online; sleep 1; done
> 
> and this as well ... without sleep ...
> 
> # for((i=0; i<100; i++)); do echo $i; echo $((i % 2))
> >/sys/devices/system/cpu/cpu1/online; done
> 
> I'm on reiserfs. gcc 3.4.5. Config sent to you seperately so as not to
> cloud lkml. If anyone wants the config, please let me know. Is mime
> "attachment" acceptable now on lkml?

It gets weirder. With "nohz=off" on commandline, I have to press any
key (generate interrupt?) for echo 1  > online to finish. 2.6.23-rc5
kernel... but hotplug/unplug works reliably now.

With nohz=off highres=off I can unplug/replug cpus as much as I
want... running in tight loop now.
								Pavel

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