Re: [PATCH] nohz: delay going tickless under CPU load to favor deeper C states

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 4/7/2011 11:18 AM, Kevin Hilman wrote:
From: Nicole Chalhoub<n-chalhoub@xxxxxx>

While there is CPU load, continue the periodic tick in order to give
CPUidle another opportunity to pick a deeper C-state instead of
spending potentially long i


so I don't really like this patch. It's actually a pretty bad hack (I'm sure it'll work somewhat)
[and I mean that in the most positive sense of the word ;-) ]

what we really need instead, and this is inside cpuidle, is the option to set a timer when we enter the non-deepest C state,
so that if that timer fires we then reevaluate.
The duration of that timer will be dependent on the C state (so should come from the C state structure of the state we pick).

For the most shallow one this will be a relatively short time, but for the deepest-but-one this might be a lot longer time.


your patch abuses a completely different, unrelated timer for this, with a pretty much unspecified frequency, that also has other side effects that we probably don't want.


it shouldn't be hard to do the right thing instead and make it a separate timer with a per C state timeout.

(and I would say a default timeout of 10x the break even time that we already have in the structure)



--
To unsubscribe from this list: send the line "unsubscribe linux-omap" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html


[Index of Archives]     [Linux Arm (vger)]     [ARM Kernel]     [ARM MSM]     [Linux Tegra]     [Linux WPAN Networking]     [Linux Wireless Networking]     [Maemo Users]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite Trails]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux