Messages in this thread | | | From | Peter Newman <> | Date | Mon, 31 Oct 2022 15:21:51 +0100 | Subject | Re: [PATCH 18/18] x86/resctrl: Separate arch and fs resctrl locks |
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Hi James,
On Fri, Oct 21, 2022 at 3:13 PM James Morse <james.morse@arm.com> wrote: > > MPAM's monitors have an overflow interrupt, so it needs to be possible > to walk the domains list in irq context. RCU is ideal for this, > but some paths need to be able to sleep to allocate memory.
I'm curious about this requirement. There are already counters which can overflow on Intel, but we've been able to detect overflows soon enough by checking at a reasonable interval. Are we expecting MSCs to have counters that overflow so quickly that the overflows need to be handled directly in IRQ context vs being able to run a threaded handler before the second overflow?
It seems like MBM would be really intrusive if it could cause the system to process overflow IRQs at a high rate.
Also is the overflow interrupt handler in one of your MPAM preview branches? I was only able to find an error IRQ handler in mpam/snapshot/v6.0:
https://git.kernel.org/pub/scm/linux/kernel/git/morse/linux.git/tree/drivers/platform/mpam/mpam_devices.c?h=mpam/snapshot/v6.0#n1813
-Peter
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