Messages in this thread | | | Date | Fri, 5 Aug 2005 10:09:19 -0700 (PDT) | From | Christoph Lameter <> | Subject | Re: [RFC] Demand faulting for large pages |
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On Fri, 5 Aug 2005, Andi Kleen wrote:
> > Unless I am missing something, the call to follow_hugetlb_page() in > > get_user_pages() is just an optimization. Removing it means > > follow_page() will be called individually for each PAGE_SIZE page in the > > huge page. We can probably do better but I didn't want to cloud this > > patch with that logic. > > The problem is that get_user_pages needs to handle the case of a large > page not yet being faulted in properly. The SLES9 implementation did > some changes for this. > > You don't change it at all, so I'm suspect it doesn't work yet. > > It's a common case - think people doing raw IO on huge pages shared memory.
Seems that follow_page calls follow_huge_addr for huge pages. follow_huge_addr is arch specific and so we would need to verify that all arches do the right things if the page is not present.
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