power management, ahci link power management and DragonFly

Alex Hornung ahornung at gmail.com
Mon Nov 8 10:29:06 PST 2010


On 08/11/2010 15:16, Johannes Hofmann wrote:
I didn't see those on my thinkpad when adding link power management.
It looks like a bug. Are you getting those for each request, or just
when activating it?
What exact type of thinkpad and harddrive do you use?
My ThinkPad is a T60 8744-HDG with a Hitachi HTS541616J9SA00 drive. And 
it happens for any request, I think. Or maybe for the first one every 
short while.

I played around with it a bit and to me it seemed that wakeups are not
that much of a big deal. E.g. decreasing HZ (just for testing) didn't
gain much. But I might be missing something as everyone in Linux-land
talks about reducing the wakups and tickless kernels.
Well, I really don't know why we are so power inefficient. Our frequency 
is already rather low at 100 Hz, but something is going on that isn't 
quite right.

Cheers,
Alex




More information about the Kernel mailing list