Robin Holt wrote: [Thu Apr 13 2006, 09:14:42AM EDT] > > This patch modifies ia64's show_mem() to walk the vmem_map page tables and > rapidly skip forward across regions where the page tables are missing. > This prevents the pfn_valid() check from causing numerous unnecessary > page faults. > > Without this patch on a 512 node 512 cpu system where every node has four > memory holes, the show_mem() call takes 1 hour 18 minutes. With this > patch, it takes less than 3 seconds. > > Signed-off-by: Robin Holt <holt@xxxxxxx> > > --- > Fixed. > > > Index: linux-2.6/arch/ia64/mm/discontig.c > =================================================================== > --- linux-2.6.orig/arch/ia64/mm/discontig.c 2006-04-13 06:16:00.500029306 -0500 > +++ linux-2.6/arch/ia64/mm/discontig.c 2006-04-13 07:01:31.668069891 -0500 > @@ -519,6 +519,69 @@ void __cpuinit *per_cpu_init(void) > } > #endif /* CONFIG_SMP */ How about these changes to fix SPARSEMEM. > > + #ifdef CONFIG_VIRTUAL_MEM_MAP > +static int find_next_valid_pfn_for_pgdat(pg_data_t *pgdat, int i) > +{ > + unsigned long end_address, hole_next_pfn; > + unsigned long stop_address; > + > + end_address = (unsigned long) &vmem_map[pgdat->node_start_pfn + i]; > + end_address = PAGE_ALIGN(end_address); > + > + stop_address = (unsigned long) &vmem_map[ > + pgdat->node_start_pfn + pgdat->node_spanned_pages]; > + > + do { > + pgd_t *pgd; > + pud_t *pud; > + pmd_t *pmd; > + pte_t *pte; > + > + pgd = pgd_offset_k(end_address); > + if (pgd_none(*pgd)) { > + end_address += PTRS_PER_PUD * > + PTRS_PER_PMD * > + PTRS_PER_PTE * > + PAGE_SIZE; > + continue; > + } > + > + pud = pud_offset(pgd, end_address); > + if (pud_none(*pud)) { > + end_address += PTRS_PER_PMD * > + PTRS_PER_PTE * > + PAGE_SIZE; > + continue; > + } > + > + pmd = pmd_offset(pud, end_address); > + if (pmd_none(*pmd)) { > + end_address += PTRS_PER_PTE * > + PAGE_SIZE; > + continue; > + } > + > + pte = pte_offset_kernel(pmd, end_address); > +retry_pte: > + if (pte_none(*pte)) { > + end_address += PAGE_SIZE; > + pte++; > + if ((end_address < stop_address) && > + (end_address != ALIGN(end_address, 1UL << PMD_SHIFT))) > + goto retry_pte; > + continue; > + } > + /* Found next valid vmem_map page */ > + break; > + } while (end_address < stop_address); > + > + end_address = min(end_address, stop_address); > + end_address = end_address - (unsigned long) vmem_map + sizeof(struct page) - 1; > + hole_next_pfn = end_address / sizeof(struct page); > + return hole_next_pfn - pgdat->node_start_pfn; > +} #else static inline int find_next_valid_pfn_for_pgdat(pg_data_t *pgdat, int i) { return i + 1; } #endif This should optimize out below for SPARSEMEM. bob > + > + > /** > * show_mem - give short summary of memory stats > * > @@ -547,8 +610,10 @@ void show_mem(void) > struct page *page; > if (pfn_valid(pgdat->node_start_pfn + i)) > page = pfn_to_page(pgdat->node_start_pfn + i); > - else > + else { > + i = find_next_valid_pfn_for_pgdat(pgdat, i) - 1; > continue; > + } > if (PageReserved(page)) > reserved++; > else if (PageSwapCache(page)) - : send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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