Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault

Andi Kleen
2010-07-16T19:28:54Z

> Actually, module loading is already a performance problem; a lot of
> distros load sometimes hundreds of modules on startup, and it's heavily

On startup you don't have many processes. If there's a problem
it's surely not the fault of vmalloc_sync_all()

BTW in my experience one reason module loading was traditionally slow was
that it did a stop_machine(). I think(?) that has been fixed
at some point. But even with that's it's more an issue on larger
systems.

> I really hope noone ever gets the idea of touching user space from an
> NMI handler, though, and expecting it to work...

It can make sense for a backtrace in a profiler.

In fact perf is nearly doing it I believe, but moves
it to the self IPI handler in most cases.

-Andi
--
ak@linux.intel.com -- Speaking for myself only.