Messages in this thread |  | | Subject | AMD Mobile Semprons (3500+, 3600+,...) break with nohz and highres enabled | From | Thomas Renninger <> | Date | Mon, 16 Jun 2008 19:47:53 +0200 |
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Hi,
we got a bit further, Evgeny was able to get C-states working with "nohz=off highres=off" boot parameters.
A short summary what has been found out that far: - apic timer breaks on C2 or deeper - noapictimer workaround helps to come a bit further, but results in sever other errors (see comment #13) - "nohz=off highres=off" works (tested on 2.6.25.4-8-pae and 2.6.22.17-0.1-default SUSE kernels) - processor.max_cstate=1 works - This affects AMD Mobile Semprons (at least 3500+ and 3600+)
The output of /proc/acp/processor/*/power without highres/nohz looks promising: states: C1: type[C1] promotion[C2] demotion[--] latency[000] usage[00000030] duration[00000000000000000000] C2: type[C2] promotion[C3] demotion[C1] latency[005] usage[00002135] duration[00000000000011279621] *C3: type[C3] promotion[--] demotion[C2] latency[020] usage[00034222] duration[00000000000228307174]
Also see bug: https://bugzilla.novell.com/show_bug.cgi?id=396220 and some posts from Richard on the linux-acpi list.
This seem to be a mainline kernel regression since the nohz/highres patches have been added. I do not own such a machine myself (Richard, Evgeny, Uli (and Anvin?) have such a machine and already helped to come that far).
Also the highres/nohz parts are a dark area to me... Any pointer how to debug (or debug patches or patches to test), where to look at, etc. is very much appreciated.
Thanks,
Thomas
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