Messages in this thread Patch in this message | | | From | Mel Gorman <> | Subject | [PATCH 6/6] Use macros instead of static inline functions for zonelist iterators | Date | Fri, 31 Aug 2007 21:53:39 +0100 (IST) |
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gcc-3.4 and probably older compiler versions produce worse code for static inline functions than they do for macros. Due to the fact the allocator path is a hotpath, there is approximately a 0.2% performance difference on kernbench's System CPU times when using static inline functions. This is not a problem on gcc 4.1.
This patch should be ignored because the static inline functions come with type-checking and there doesn't need to be concern about macro arguements having funky side-effects. However, as the performance problem is noticable on older compilers, the compiler version and this patch should be checked as the potential source and solution to a performance regression.
Signed-off-by: Mel Gorman <mel@csn.ul.ie> ---
include/linux/gfp.h | 8 ++++---- include/linux/mmzone.h | 31 +++++++++++++++++++------------ 2 files changed, 23 insertions(+), 16 deletions(-)
diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.23-rc3-mm1-040_use_one_zonelist/include/linux/gfp.h linux-2.6.23-rc3-mm1-045_macro_not_inline/include/linux/gfp.h --- linux-2.6.23-rc3-mm1-040_use_one_zonelist/include/linux/gfp.h 2007-08-31 17:22:55.000000000 +0100 +++ linux-2.6.23-rc3-mm1-045_macro_not_inline/include/linux/gfp.h 2007-08-31 17:23:10.000000000 +0100 @@ -156,11 +156,11 @@ static inline gfp_t set_migrateflags(gfp * * For the normal case of non-DISCONTIGMEM systems the NODE_DATA() gets * optimized to &contig_page_data at compile-time. + * + * See the explanation above zonelist_zone() in include/linux/mmzone.h as + * to why this is a macro and not a static inline */ -static inline struct zonelist *node_zonelist(int nid) -{ - return &NODE_DATA(nid)->node_zonelist; -} +#define node_zonelist(nid) (&NODE_DATA(nid)->node_zonelist) #ifndef HAVE_ARCH_FREE_PAGE static inline void arch_free_page(struct page *page, int order) { } diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.23-rc3-mm1-040_use_one_zonelist/include/linux/mmzone.h linux-2.6.23-rc3-mm1-045_macro_not_inline/include/linux/mmzone.h --- linux-2.6.23-rc3-mm1-040_use_one_zonelist/include/linux/mmzone.h 2007-08-31 18:06:59.000000000 +0100 +++ linux-2.6.23-rc3-mm1-045_macro_not_inline/include/linux/mmzone.h 2007-08-31 17:23:10.000000000 +0100 @@ -687,15 +687,16 @@ extern struct zone *next_zone(struct zon #endif #define ZONELIST_ZONEIDX_MASK ((1UL << ZONES_SHIFT) - 1) -static inline struct zone *zonelist_zone(unsigned long zone_addr) -{ - return (struct zone *)(zone_addr & ~ZONELIST_ZONEIDX_MASK); -} -static inline int zonelist_zone_idx(unsigned long zone_addr) -{ - return zone_addr & ZONELIST_ZONEIDX_MASK; -} +/* + * Subtle: These are macros, not static inlines because gcc 3.4 at least + * produces worse code with static inline functions. The effect is about 0.4% + * regression in kernbench tests. The problem doesn't appear to exist on + * gcc 4.1 + */ +#define zonelist_zone_idx(zone_addr) ((zone_addr) & ZONELIST_ZONEIDX_MASK) +#define zonelist_zone(zone_addr) \ + ((struct zone *)((zone_addr) & ~ZONELIST_ZONEIDX_MASK)) static inline unsigned long encode_zone_idx(struct zone *zone) { @@ -706,13 +707,19 @@ static inline unsigned long encode_zone_ return encoded; } -static inline int zone_in_nodemask(unsigned long zone_addr, nodemask_t *nodes) -{ #ifdef CONFIG_NUMA - return node_isset(zonelist_zone(zone_addr)->node, *nodes); +#define zone_in_nodemask(zone_addr, nodes) \ + (node_isset(zonelist_zone(zone_addr)->node, *nodes)) #else - return 1; +#define zone_in_nodemask(zone_addr, nodes) (1) #endif /* CONFIG_NUMA */ + +static inline int zone_in_nodemask(unsigned long zone_addr, nodemask_t *nodes) +{ + if (NUMA_BUILD) + return node_isset(zonelist_zone(zone_addr)->node, *nodes); + + return 1; } /* Returns the first zone at or below highest_zoneidx in a zonelist */ - 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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