Re: Power consumption HZ100, HZ250, HZ1000: new numbers

James Bruce
2005-08-03T16:49:49Z

(Sorry all, but after receiving about 5 similar messages I'm going to
make one last reply.)

ambx1@neo.rr.com wrote:
> Also, my understanding was that when we properly support usb suspend,
> this won't be an issue anyway for much usb hardware. I think it's
> possible to put some mice to sleep when there isn't any motion and
> then wakeup later.

By the time we properly support USB suspend, it won't matter because the
dynamic tick patch will likely have been integrated. An argument for
why we should change a value in the future is pointless when the
question is what the value should be right now.

> 4.4% savings may not be much, but these things do add up.

A 300% increase in minimum sleep latency adds up quite quickly.

The point that people joining this thread keep missing is that we're
making a change that:
(a) offers a small benefit to laptop users
(b) messes up other uses such as video
(c) is likely to be completely obsolete by 2.6.14

> For a laptop's workload, I think this is worth it.

Good, so on your laptop go choose 100Hz. You already have to configure
your kernel to change values from their defaults anyway, otherwise you
won't see any of that 4.4% savings. However, please don't screw up
video and interactivity (1) for everyone who uses default values on
their desktops in order to get your savings.

(1) http://article.gmane.org/gmane.linux.kernel/319124/

Rather like the famous gcc 2.96, this is something that will confuse
users for some time to come. Just about every video app will need an
FAQ entry to say why 2.6.13 doesn't work as well and drops frames while
2.6.(x!=13) works just fine. Unless of course distros read this thread
and decide not to pick up this change; That I guess is the only reason
I'm still posting.

Now as Lee said, please let this thread die. We need to go work on
dyntick and test it on as much hardware as possible and try to uncover
any lurking bugs. If you care about saving power or multimedia, you
should test it too (think ~10% savings rather than 4.4%).

- Jim Bruce