Re: Page fault scalability patch V18: Drop first acquisition of ptl

From: Benjamin Herrenschmidt <>
Date: 2005-03-03 16:54:08
> However, if this pte_cmpxchg() thing is used for removing access, then
> sparc64 can't use it.  In such a case a race in the TLB handler would
> result in using an invalid PTE.  I could "spin" on some lock bit, but
> there is no way I'm adding instructions to the carefully constructed
> TLB miss handler assembler on sparc64 just for that :-)

Can't you add a lock bit in the PTE itself like we do on ppc64 hash
refill ?

Ok, ok, you don't want to add instructions, fair enough :) On ppc64, I
had to do that to close some nasty race we had in the hash refill, but
it came almost for free as we already had an atomic loop in there.


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Received on Thu Mar 3 01:01:25 2005

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