Pallipadi, Venkatesh wrote:
-----Original Message-----
From: Mark Lord [mailto:lkml@xxxxxx]
..
Okay, with !CONFIG_CPU_IDLE, this works fine -- same as 2.6.23
and earlier.
Good to know. Atleast we do not have a regression for 2.6.24 now.
..
Agreed. We're happy here, for now.
Meanwhile, can you give a short summary of how behaviour differs
between CONFIG_CPU_IDLE and !CONFIG_CPU_IDLE ??
I'm not at all clear on how this really affects things.
With CPU_IDLE, the C-state policy is removed from acpi driver. Ideally
policy should have nothing to do with ACPI, as ACPI only provides the
C-state mechanisms. So, with CPU_IDLE, it is not easy to control this
variable through a acpi driver module at run time. Also, the latency
interface that was mentioned before is to serve the same purpose in a
more clear manner (based on the wakeup latency) instead of a C-state
number which may not mean much from the end user point of view.
I will look at why latency does not work on a single core system
soon(Was that with UP kernel or SMP kernel?). That way we will have a
proper cover for this with CPU_IDLE in future.
..
That was with a UP kernel on a UP box.
The latency thingie really seemed to have little or no effect,
whereas setting max_cstate=1 has a quite noticeable positive impact.
Things seemed okay (with the latency thingie) on the SMP machine,
but with two cores it is probably simply more forgiving.
cheers
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