Messages in this thread | | | Date | Tue, 21 Mar 2006 10:20:12 -0500 | From | "Stone Wang" <> | Subject | Re: [PATCH][0/8] (Targeting 2.6.17) Posix memory locking and balanced mlock-LRU semantic |
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Checked, mlocked pages dont take part in swapping-writeback, unlike normal mmaped pages :
linux-2.6.16/mm/rmap.c
try_to_unmap_one()
603 if ((vma->vm_flags & VM_LOCKED) || 604 (ptep_clear_flush_young(vma, address, pte) 605 && !ignore_refs)) { 606 ret = SWAP_FAIL; 607 goto out_unmap; 608 } 609 610 /* Nuke the page table entry. */ 611 flush_cache_page(vma, address, page_to_pfn(page)); 612 pteval = ptep_clear_flush(vma, address, pte); 613 614 /* Move the dirty bit to the physical page now the pte is gone. */ 615 if (pte_dirty(pteval)) 616 set_page_dirty(page);
For VM_LOCKED page, it goes back(line 607) without set_page_dirty(line 616).
2006/3/20, Christoph Lameter <clameter@sgi.com>: > On Mon, 20 Mar 2006, Stone Wang wrote: > > > 2. More consistent LRU semantics in Memory Management. > > Mlocked pages is placed on a separate LRU list: Wired List. > > The pages dont take part in LRU algorithms,for they could never be swapped, > > until munlocked. > > This also implies that dirty bits of the pte for mlocked pages are never > checked. > > Currently light swapping (which is very common) will scan over all pages > and move the dirty bits from the pte into struct page. This may take > awhile but at least at some point we will write out dirtied pages. > > The result of not scanning mlocked pages will be that mmapped files will > not be updated unless either the process terminates or msync() is called. > > - 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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