Messages in this thread | | | From | David Brownell <> | Subject | Re: 2.6.25 regression: powertop says 120K wakeups/sec | Date | Fri, 28 Mar 2008 12:01:53 -0700 |
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On Saturday 22 March 2008, Andrew Morton wrote: > On Sat, 22 Mar 2008 13:24:54 -0700 David Brownell <david-b@pacbell.net> wrote: > > > I noticed this with 2.6.25-rc2 (if not before), and the problem > > is still there with 2.6.25-rc6-git (as of this AM).
A 2.6.24 kernel I still had stashed away didn't act odd; the problem joined us before 2.6.25-rc1 was tagged.
> > System is an Athlon64 single CPU laptop, and instead of reading a > > few dozen wakeups per second, it says a many tens of thousands... > > clearly wrong. In previous kernels it gave more plausible counts; > > unfortunately high because of various un-evolved desktop tools in > > this Ubuntu system (Feisty). > > > > Possibly more truthful, it says that the system never enters > > C1 or C2, and spends all its time in C0. Though if I look at > > /sys/devices/system/cpu/cpu0/cpuidle/state[01]/usage, that > > seems to tell a different story ... it's C0 that's never used. > > In previous kernels it reported time in both C0 and C2. ISTR > > some patch to avoid C2, which would explain part of this. > > > > Comments or fixes, anyone? > > This is likely to be an acpi regression, isn't it? > > A git-bisect would be nice, please.
The git-bisect says the 120K wakeups/second comes from a patch which unfortunately can't be directly reverted, so I didn't verify that reverting it resolves that problem. I've not tried to do anything with the other C0/C1/C2 stuff.
$ git bisect good bc71bec91f9875ef825d12104acf3bf4ca215fa4 is first bad commit commit bc71bec91f9875ef825d12104acf3bf4ca215fa4 Author: venkatesh.pallipadi@intel.com <venkatesh.pallipadi@intel.com> Date: Thu Jan 31 17:35:04 2008 -0800
ACPI: enable MWAIT for C1 idle
Add MWAIT idle for C1 state instead of halt, on platforms that support C1 state with MWAIT.
Renames cx->space_id to something more appropriate.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Signed-off-by: Len Brown <len.brown@intel.com>
:040000 040000 88ebe48d024f7fb21237cd75dbc9c681c43252b1 8af87317facbd018b47e717ede6907d9a831f92c M drivers :040000 040000 ecd73d87c1b7b7004e06ffa3a2b3e7260c045543 934c38290353186cbaaaf27094d5c1712e548fcc M include $
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