Messages in this thread | | | Date | Fri, 16 Jul 2010 14:22:40 -0400 | From | Mathieu Desnoyers <> | Subject | Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault |
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* Avi Kivity (avi@redhat.com) wrote: > On 07/16/2010 09:05 PM, H. Peter Anvin wrote: >> >>> Module loading can certainly take a vmalloc_sync_all() (though I agree >>> it's unpleasant). Anything else? >>> >>> Note perf is not modular at this time, but could be made so with >>> preempt/sched notifiers to hook the context switch. >>> >>> >> Actually, module loading is already a performance problem; a lot of >> distros load sometimes hundreds of modules on startup, and it's heavily >> serialized, so I can see this being desirable to skip. >> > > There aren't that many processes at this time (or there shouldn't be, > don't know how fork-happy udev is at this stage), so the sync should be > pretty fast. In any case, we can sync only modules that contain NMI > handlers.
USB hotplug is a use-case happening randomly after the system is well there and running; I'm afraid this does not fit in your module loading expectations. It triggers tons of events, many of these actually load modules.
Thanks,
Mathieu
> >> I really hope noone ever gets the idea of touching user space from an >> NMI handler, though, and expecting it to work... >> > > I think the concern here is about an NMI handler's code running in > vmalloc space, or is it something else? > > -- > I have a truly marvellous patch that fixes the bug which this > signature is too narrow to contain. >
-- Mathieu Desnoyers Operating System Efficiency R&D Consultant EfficiOS Inc. http://www.efficios.com
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