Re: [RFC] maximum latency tracking infrastructure

[Jesse Barnes <jbarnes@virtuousgeek.org>]

On Thursday, August 24, 2006 10:41 am, Arjan van de Ven wrote:
> The reason for adding this infrastructure is that power management in
> the idle loop needs to make a tradeoff between latency and power
> savings (deeper power save modes have a longer latency to running code
> again).

What if a processor was already in a sleep state when a call to 
set_acceptable_latency() latency occurs?  Should there be a callback so 
they can be woken up?  A callback would also allow ACPI to tell the 
user "disabling C3 because of device <foo>" or somesuch, which might be 
nice.

Also, should subsystems have the ability to set a lower bound on  
latency?  That would mean set_acceptable_latency() could fail, 
indicating that the user should buy a better device or a system with 
better realtime guarantees, which is also valuable info.

Comments aside, this is a nice interface, should help clarify things for 
devices with response time limits.

Thanks,
Jesse