Messages in this thread Patch in this message | | | From | Mel Gorman <> | Subject | [PATCH 4/8] Add a configure option for anti-fragmentation | Date | Thu, 7 Sep 2006 20:05:02 +0100 (IST) |
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The anti-fragmentation strategy has memory overhead. This patch allows the strategy to be disabled for small memory systems or if it is known the workload is suffering because of the strategy. It also acts to show where the anti-frag strategy interacts with the standard buddy allocator.
Signed-off-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Joel Schopp <jschopp@austin.ibm.com> ---
init/Kconfig | 14 ++++++++++++++ mm/page_alloc.c | 20 ++++++++++++++++++++ 2 files changed, 34 insertions(+)
diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.18-rc5-mm1-003_percpu/init/Kconfig linux-2.6.18-rc5-mm1-004_configurable/init/Kconfig --- linux-2.6.18-rc5-mm1-003_percpu/init/Kconfig 2006-09-04 18:34:33.000000000 +0100 +++ linux-2.6.18-rc5-mm1-004_configurable/init/Kconfig 2006-09-04 18:41:13.000000000 +0100 @@ -478,6 +478,20 @@ config SLOB default !SLAB bool +config PAGEALLOC_ANTIFRAG + bool "Avoid fragmentation in the page allocator" + def_bool n + help + The standard allocator will fragment memory over time which means + that high order allocations will fail even if kswapd is running. If + this option is set, the allocator will try and group page types into + two groups, kernel and easy reclaimable. The gain is a best effort + attempt at lowering fragmentation which a few workloads care about. + The loss is a more complex allocactor that may perform slower. If + you are interested in working with large pages, say Y and set + /proc/sys/vm/min_free_bytes to be 10% of physical memory. Otherwise + say N + menu "Loadable module support" config MODULES diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.18-rc5-mm1-003_percpu/mm/page_alloc.c linux-2.6.18-rc5-mm1-004_configurable/mm/page_alloc.c --- linux-2.6.18-rc5-mm1-003_percpu/mm/page_alloc.c 2006-09-04 18:39:39.000000000 +0100 +++ linux-2.6.18-rc5-mm1-004_configurable/mm/page_alloc.c 2006-09-04 18:41:13.000000000 +0100 @@ -133,6 +133,7 @@ static unsigned long __initdata dma_rese unsigned long __initdata arch_zone_highest_possible_pfn[MAX_NR_ZONES]; #endif /* CONFIG_ARCH_POPULATES_NODE_MAP */ +#ifdef CONFIG_PAGEALLOC_ANTIFRAG static inline int get_pageblock_type(struct page *page) { return (PageEasyRclm(page) != 0); @@ -142,6 +143,17 @@ static inline int gfpflags_to_rclmtype(u { return ((gfp_flags & __GFP_EASYRCLM) != 0); } +#else +static inline int get_pageblock_type(struct page *page) +{ + return RCLM_NORCLM; +} + +static inline int gfpflags_to_rclmtype(unsigned long gfp_flags) +{ + return RCLM_NORCLM; +} +#endif /* CONFIG_PAGEALLOC_ANTIFRAG */ #ifdef CONFIG_DEBUG_VM static int page_outside_zone_boundaries(struct zone *zone, struct page *page) @@ -638,6 +650,7 @@ static int prep_new_page(struct page *pa return 0; } +#ifdef CONFIG_PAGEALLOC_ANTIFRAG /* Remove an element from the buddy allocator from the fallback list */ static struct page *__rmqueue_fallback(struct zone *zone, int order, gfp_t gfp_flags) @@ -676,6 +689,13 @@ static struct page *__rmqueue_fallback(s return NULL; } +#else +static struct page *__rmqueue_fallback(struct zone *zone, unsigned int order, + int rclmtype) +{ + return NULL; +} +#endif /* CONFIG_PAGEALLOC_ANTIFRAG */ /* * Do the hard work of removing an element from the buddy allocator. - 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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