Re: [RFC PATCH v2 03/19] vbus: add connection-client helper infrastructure

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Gregory Haskins wrote:
Oh, I don't doubt that (in fact, I was pretty sure that was the case
based on some of the optimizations I could see in studying the c_t_u()
path).  I just didn't realize there were other ways to do it if its a
non "current" task. ;)

I guess the enigma for me right now is what cost does switch_mm have? (Thats not a slam against the suggested approach...I really do not know
and am curious).

switch_mm() is probably very cheap (reloads cr3), but it does dirty the current cpu's tlb. When the kernel needs to flush a process' tlb, it will have to IPI that cpu in addition to all others. This takes place, for example, after munmap() or after a page is swapped out (though significant batching is done there).

It's still plenty cheaper in my estimation.

--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.

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