lkml.org 
[lkml]   [2010]   [Jan]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: acpi_idle: Very idle Core i7 machine never enters C3
    From
    Date
    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.


    \
     
     \ /
      Last update: 2010-01-26 22:47    [W:3.838 / U:0.668 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site