On Sat, 26 Feb 2011 22:56:31 +0800 Nai Xia <nai.xia@xxxxxxxxx> wrote: > ksm_pages_sharing is updated by ksmd periodically. In some cases, it cannot > reflect the actual savings and makes the benchmarks on volatile VMAs very > inaccurate. > > This patch add a vm_stat entry and let the /proc/meminfo show information > about how much virutal address pte is being mapped to ksm pages. With default > ksm paramters (pages_to_scan==100 && sleep_millisecs==20), this can result in > 50% more accurate averaged savings result for the following test program. > Bigger sleep_millisecs values will increase this deviation. > > ... > > --- a/fs/proc/meminfo.c > +++ b/fs/proc/meminfo.c > @@ -87,6 +87,9 @@ static int meminfo_proc_show(struct seq_file *m, void *v) > "SUnreclaim: %8lu kB\n" > "KernelStack: %8lu kB\n" > "PageTables: %8lu kB\n" > +#ifdef CONFIG_KSM > + "KsmSharing: %8lu kB\n" > +#endif > #ifdef CONFIG_QUICKLIST > "Quicklists: %8lu kB\n" > #endif > > ... > > @@ -904,6 +905,10 @@ static int try_to_merge_one_page(struct vm_area_struct > *vma, > */ > set_page_stable_node(page, NULL); > mark_page_accessed(page); > + if (mapcount) > + add_zone_page_state(page_zone(page), > + NR_KSM_PAGES_SHARING, > + mapcount); > err = 0; > } else if (pages_identical(page, kpage)) > err = replace_page(vma, page, kpage, orig_pte); This patch obviously wasn't tested with CONFIG_KSM=n, which was a pretty basic patch-testing failure :( I fixed up my tree with the below, but really the amount of ifdeffing is unacceptable - please find a cleaner way to fix up this patch. --- a/mm/ksm.c~ksm-add-vm_stat-and-meminfo-entry-to-reflect-pte-mapping-to-ksm-pages-fix +++ a/mm/ksm.c @@ -883,7 +883,6 @@ static int try_to_merge_one_page(struct */ if (write_protect_page(vma, page, &orig_pte) == 0) { if (!kpage) { - long mapcount = page_mapcount(page); /* * While we hold page lock, upgrade page from * PageAnon+anon_vma to PageKsm+NULL stable_node: @@ -891,10 +890,12 @@ static int try_to_merge_one_page(struct */ set_page_stable_node(page, NULL); mark_page_accessed(page); - if (mapcount) +#ifdef CONFIG_KSM + if (page_mapcount(page)) add_zone_page_state(page_zone(page), NR_KSM_PAGES_SHARING, mapcount); +#endif err = 0; } else if (pages_identical(page, kpage)) err = replace_page(vma, page, kpage, orig_pte); --- a/mm/memory.c~ksm-add-vm_stat-and-meminfo-entry-to-reflect-pte-mapping-to-ksm-pages-fix +++ a/mm/memory.c @@ -719,8 +719,10 @@ copy_one_pte(struct mm_struct *dst_mm, s rss[MM_ANONPAGES]++; else rss[MM_FILEPAGES]++; +#ifdef CONFIG_KSM if (PageKsm(page)) /* follows page_dup_rmap() */ inc_zone_page_state(page, NR_KSM_PAGES_SHARING); +#endif } out_set_pte: --- a/mm/rmap.c~ksm-add-vm_stat-and-meminfo-entry-to-reflect-pte-mapping-to-ksm-pages-fix +++ a/mm/rmap.c @@ -893,11 +893,12 @@ void do_page_add_anon_rmap(struct page * __inc_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES); } +#ifdef CONFIG_KSM if (unlikely(PageKsm(page))) { __inc_zone_page_state(page, NR_KSM_PAGES_SHARING); return; } - +#endif VM_BUG_ON(!PageLocked(page)); VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end); if (first) @@ -955,9 +956,10 @@ void page_add_file_rmap(struct page *pag */ void page_remove_rmap(struct page *page) { +#ifdef CONFIG_KSM if (PageKsm(page)) __dec_zone_page_state(page, NR_KSM_PAGES_SHARING); - +#endif /* page still mapped by someone else? */ if (!atomic_add_negative(-1, &page->_mapcount)) return; _ -- To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html