Messages in this thread | | | Date | Wed, 4 Nov 2009 10:19:29 -0500 | From | Aristeu Rozanski <> | Subject | Re: [PATCH 2/2] x86: introduce NMI_AUTO as nmi_watchdog option |
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> > NMI_AUTO is a new nmi_watchdog option that makes LAPIC be tried first > > and if the CPU isn't supported, IOAPIC will be used. It's useful in > > cases where NMI watchdog is enabled by default in a kernel built for > > different machines. It can be configured by default or selected with > > nmi_watchdog=3 or nmi_watchdog=auto parameters. > > What i'd like to see for the NMI watchdog is much more ambitious than > this: the use of perf events to run a periodic NMI callback. > > The NMI watchdog would cause the creation of a per-cpu perf_event > structure (in-kernel). All x86 CPUs that have perf event support (the > majority of them) will thus be able to have an NMI watchdog using a > nice, generic piece of code and we'd be able to phase out the open-coded > NMI watchdog code. > > The user would not notice much from this: we'd still have the > /proc/sys/kernel/nmi_watchdog toggle to turn it on/off, and we'd still > have the nmi_watchog= boot parameter as well. But the underlying > implementation would be far more generic and far more usable than the > current code. > > Would you be interested in moving the NMI watchdog code in this > direction? Most of the perf events changes (callbacks, helpers for > in-kernel event allocations, etc.) are in latest -tip already, so you > could use that as a base. but that would work only for LAPIC. You're suggesting killing IOAPIC mode too?
-- Aristeu
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