On śro, 2015-02-04 at 08:28 -0800, Paul E. McKenney wrote: > On Wed, Feb 04, 2015 at 05:10:56PM +0100, Krzysztof Kozlowski wrote: > > On śro, 2015-02-04 at 07:56 -0800, Paul E. McKenney wrote: > > > On Wed, Feb 04, 2015 at 04:22:28PM +0100, Krzysztof Kozlowski wrote: > > > > > > > > Actually the timeout versions but I think that doesn't matter. > > > > The wait_on_bit will busy-loop with testing for the bit. Inside the loop > > > > it calls the 'action' which in my case will be bit_wait_io_timeout(). > > > > This calls schedule_timeout(). > > > > > > Ah, good point. > > > > > > > See proof of concept in attachment. One observed issue: hot unplug from > > > > commandline takes a lot more time. About 7 seconds instead of ~0.5. > > > > Probably I did something wrong. > > > > > > Well, you do set the timeout to five seconds, and so if the condition > > > does not get set before the surviving CPU finds its way to the > > > out_of_line_wait_on_bit_timeout(), you are guaranteed to wait for at > > > least five seconds. > > > > > > One alternative approach would be to have a loop around a series of > > > shorter waits. Other thoughts? > > > > Right! That was the issue. It seems it works. I'll think also on > > self-adapting interval as you said below. I'll test it more and send a > > patch. > > Sounds good! > > Are you doing ARM, ARM64, or both? I of course vote for both. ;-)
I'll do both but first I need to find who has ARM64 board in my team. Best regards, Krzysztof -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
