Thread (58 messages) 58 messages, 4 authors, 2009-10-05

Re: [PATCH] powerpc/8xx: fix regression introduced by cache coherency rewrite

From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: 2009-09-25 01:51:29

On Thu, 2009-09-24 at 18:35 -0700, Rex Feany wrote:
Then I can boot and get to a shell, but userspace is slow. 8 seconds
to mount
/proc (vs. less then a second using my old kernel)! Maybe this is an
unrelated issue?  I'm pretty clueless about the details, I'm sorry.
PG_arch_1 is used to prevent a cache flush unless it is actually
needed?
Then why would changing the location of the tlbil_va() make a
difference?
I think there's more finishyness to 8xx than we thought. IE. That
tlbil_va might have more reasons to be there than what the comment
seems to advertize. Can you try to move it even higher up ? IE.
Unconditionally at the beginning of set_pte_filter ?

Also, if that doesn't help, can you try putting one in
set_access_flags_filter() just below ?

(Beware that there's two different versions of both functions, only the
first one is compiled/used on 8xx).

It's going to be hard for me to get that "right" since I don't really
know what's going on with the core here, but I suppose if we get it
moving along with extra tlb invalidations, that should be "good enough"
until somebody who really knows what's going on comes up with possibly
a better fix.

Cheers,
Ben.
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