Messages in this thread | | | Date | Sat, 8 May 2004 23:39:32 +0100 (BST) | From | Hugh Dickins <> | Subject | Re: [PATCH] rmap 24 pte_young first |
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rmap 25 of course
On Sat, 8 May 2004, Christoph Hellwig wrote: > On Sat, May 08, 2004 at 10:56:26PM +0100, Hugh Dickins wrote: > > > > - if (ptep_test_and_clear_young(pte)) > > + if (pte_young(*pte) && ptep_test_and_clear_young(pte)) > > stupid question - shouldn't the pte_young check simply move to > the beginning of ptep_test_and_clear_young?
I don't think that would be a good idea. We're used to those test_and_clear operations being atomic, putting an initial non-atomic test inside would make it fundamentally non-atomic. We know here that it's not the end of the world if we miss a racing transition of the young bit, but it wouldn't be good to hide and force that on others.
Hugh
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