Messages in this thread | | | Date | Sat, 13 Mar 2004 19:16:06 +0100 | From | Andrea Arcangeli <> | Subject | Re: anon_vma RFC2 |
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On Sat, Mar 13, 2004 at 12:55:09PM -0500, Rajesh Venkatasubramanian wrote: > > > The only problem is mremap() after a fork(), and hell, we know that's a > > special case anyway, and let's just add a few lines to copy_one_pte(), > > which basically does: > > > > if (PageAnonymous(page) && page->count > 1) { > > newpage = alloc_page(); > > copy_page(page, newpage); > > page = newpage; > > } > > /* Move the page to the new address */ > > page->index = address >> PAGE_SHIFT; > > > > and now we have zero special cases. > > This part makes the problem so simple. If this is acceptable, then we > have many choices. Since we won't have many mms in the anonmm list, > I don't think we will have any search complexity problems. If we really > worry again about search complexity, we can consider using prio_tree > (adds 16 bytes per vma - we cannot share vma.shared.prio_tree_node). > The prio_tree easily fits for anonmm after linus-mremap-simplification.
prio_tree with linus-mremap-simplification makes no sense to me. You cannot avoid checking all the mm with the prio_tree and that is the only complexity issue introduced by anonmm vs anon_vma.
prio_tree can only sit on top of anon_vma, not on top of anonmm+linus-unshare-mremap (and yes, I cannot share vma.shared.prio_tree_node) but pratically it's not needed for the anon_vmas. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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