Messages in this thread | | | Date | Fri, 16 Jul 2010 21:15:25 +0300 | From | Avi Kivity <> | Subject | Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault |
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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.
> 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.
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