[PATCH] arm: sched: stop sched_clock() during suspend

Russell King - ARM Linux [off-list ref] writes:

On Tue, Oct 23, 2012 at 12:28:32AM +0200, Linus Walleij wrote:

quoted

On Mon, Oct 22, 2012 at 7:05 PM, Kevin Hilman
[off-list ref] wrote:

quoted

However, in light of RT throttling, this a correctness issue for process
accounting, so I agree that this should be done for all platforms
instead of providing an optional 'needs suspend' version of the API,
even though it means printk times no longer reflect time spent
suspended.

Maybe we should get printk() to use the best clocksource
instead.

The reason AFAICT that printk() is using sched_clock() is that
it's supposed to be fast. But now it seems that it's not going
to return what printk() needs anymore.

No, printk() does not need this.  You think it does, but it doesn't.  What
we have is a difference between ARM and x86, and this difference is breaking
the scheduler.

The fact that the printk timestamp increments while suspended is a bug.  It
doesn't on x86.

Russell, I agree that it's a bug, but does it qualify as a something
you're willing to take for v3.7-rc?

For OMAP, we need to know if this will go for v3.7 or not because
there's a regression in the OMAP I2C driver, and if this doesn't go in,
we'll need to revert something in the I2C driver until it does.

Thanks,

Kevin