Messages in this thread | | | Date | Mon, 20 Jun 2011 13:57:15 +0100 | From | Russell King - ARM Linux <> | Subject | Re: [RFC PATCH] ARM: smp: Fix the CPU hotplug race with scheduler. |
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On Mon, Jun 20, 2011 at 05:57:01PM +0530, Santosh Shilimkar wrote: > On 6/20/2011 5:49 PM, Russell King - ARM Linux wrote: >> On Mon, Jun 20, 2011 at 05:21:48PM +0530, Santosh Shilimkar wrote: >>> On 6/20/2011 5:10 PM, Russell King - ARM Linux wrote: > > [...] > >>> >>> Any pointers on the other question about "why we need to enable >>> interrupts before the CPU is ready?" >> >> To ensure that things like the delay loop calibration and twd calibration >> can run, though that looks like it'll run happily enough with the boot >> CPU updating jiffies. >> > I guessed it and had same point as above. Calibration will still > work. > >> However, I'm still not taking your patch because I believe its just >> papering over the real issue, which is not as you describe. >> >> You first need to work out why the spinlock lockup detection is firing >> after just 61us rather than the full 1s and fix that. >> > This is possibly because of my script which doesn't wait for 1 > second.
How could a userspace script affect the internal behaviour of spin_lock() and the spinlock lockup detector?
> Latest mainline kernel with omap2plus_defconfig and below simple script > to trigger the failure. > > ------------- > while true > do > echo 0 > /sys/devices/system/cpu/cpu1/online > echo 1 > /sys/devices/system/cpu/cpu1/online > done
Thanks, I'll give it a go here and see if I can debug it further.
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