Messages in this thread | | | Subject | Re: acpi_idle: Very idle Core i7 machine never enters C3 | From | Andi Kleen <> | Date | Tue, 26 Jan 2010 22:45:20 +0100 |
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jeff@jgarrett.org (Jeff Garrett) writes:
> Hi, > > I was trying to chase down a theory that my desktop machine (a core i7) > is running warm (the fan sounds like it's at full speed all the time, > and I think it's not always acted this way -- hence the theory). > > powertop is never showing it spending any time in C3... > > I compiled a kernel without USB/sound/radeon, and ran without X. I was > able to get the wakeups/sec down below 20, but no time is spent in C3.
[...] > This may be a complete red herring, but I added some printk logic to > acpi_idle_bm_check(), and it is getting called often, but bm_status is > always 1. [I infer from this that the idle logic is trying to go into > C3, but this check is stopping it... Unless I misread something.]
Normally a Core i7 (or any modern Intel systems) should not use bm_check at all. That's only for older systems that didn't support MWAIT with c-state hint, but relied on the old port based interface.
So something is already confused there.
I think it should still work though. Of course if you really have a lot of bus mastering in the background then yes there will be no C3.
-Andi
-- ak@linux.intel.com -- Speaking for myself only.
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