Single Zone Optimizations If we only have a single zone then various macros can be optimized. We do not need to protect higher zones, we know that zones are always present, can remove useless data from /proc etc etc. Signed-off-by: Christoph Lameter Index: linux-2.6.19-rc1-mm1/mm/vmstat.c =================================================================== --- linux-2.6.19-rc1-mm1.orig/mm/vmstat.c 2006-10-17 13:07:50.889011218 -0500 +++ linux-2.6.19-rc1-mm1/mm/vmstat.c 2006-10-17 13:08:06.245789164 -0500 @@ -554,15 +554,16 @@ static int zoneinfo_show(struct seq_file for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++) seq_printf(m, "\n %-12s %lu", vmstat_text[i], zone_page_state(zone, i)); - - seq_printf(m, - "\n protection: (%lu", - zone->lowmem_reserve[0]); - for (i = 1; i < ARRAY_SIZE(zone->lowmem_reserve); i++) - seq_printf(m, ", %lu", zone->lowmem_reserve[i]); - seq_printf(m, - ")" - "\n pagesets"); + if (MULTI_ZONE) { + seq_printf(m, + "\n protection: (%lu", + zone->lowmem_reserve[0]); + for (i = 1; i < ARRAY_SIZE(zone->lowmem_reserve); i++) + seq_printf(m, ", %lu", zone->lowmem_reserve[i]); + seq_printf(m, + ")" + "\n pagesets"); + } for_each_online_cpu(i) { struct per_cpu_pageset *pageset; int j; Index: linux-2.6.19-rc1-mm1/mm/page_alloc.c =================================================================== --- linux-2.6.19-rc1-mm1.orig/mm/page_alloc.c 2006-10-17 13:07:50.897801030 -0500 +++ linux-2.6.19-rc1-mm1/mm/page_alloc.c 2006-10-17 13:09:25.695921859 -0500 @@ -59,6 +59,7 @@ int percpu_pagelist_fraction; static void __free_pages_ok(struct page *page, unsigned int order); +#if MULTI_ZONE /* * results with 256, 32 in the lowmem_reserve sysctl: * 1G machine -> (16M dma, 800M-16M normal, 1G-800M high) @@ -81,6 +82,7 @@ int sysctl_lowmem_reserve_ratio[MAX_NR_Z 32 #endif }; +#endif EXPORT_SYMBOL(totalram_pages); @@ -922,8 +924,7 @@ int zone_watermark_ok(struct zone *z, in min -= min / 2; if (alloc_flags & ALLOC_HARDER) min -= min / 4; - - if (free_pages <= min + z->lowmem_reserve[classzone_idx]) + if (free_pages <= min + MULTI_ZONE * z->lowmem_reserve[classzone_idx]) return 0; for (o = 0; o < order; o++) { /* At the next order, this order's pages become unavailable */ @@ -1429,8 +1430,6 @@ void show_free_areas(void) global_page_state(NR_PAGETABLE)); for_each_zone(zone) { - int i; - if (!populated_zone(zone)) continue; @@ -1457,10 +1456,14 @@ void show_free_areas(void) zone->pages_scanned, (zone->all_unreclaimable ? "yes" : "no") ); - printk("lowmem_reserve[]:"); - for (i = 0; i < MAX_NR_ZONES; i++) - printk(" %lu", zone->lowmem_reserve[i]); - printk("\n"); + if (MULTI_ZONE) { + int i; + + printk("lowmem_reserve[]:"); + for (i = 0; i < MAX_NR_ZONES; i++) + printk(" %lu", zone->lowmem_reserve[i]); + printk("\n"); + } } for_each_zone(zone) { @@ -2829,25 +2832,36 @@ void __init page_alloc_init(void) * calculate_totalreserve_pages - called when sysctl_lower_zone_reserve_ratio * or min_free_kbytes changes. */ +static unsigned long calculate_max_lowmem_reserve(struct zone *zone, + enum zone_type start) +{ + unsigned long max; + enum zone_type i; + + if (SINGLE_ZONE) + return 0; + /* Find valid and maximum lowmem_reserve in the zone */ + for (i = start; i < MAX_NR_ZONES; i++) { + if (zone->lowmem_reserve[i] > max) + max = zone->lowmem_reserve[i]; + } + return max; +} + static void calculate_totalreserve_pages(void) { struct pglist_data *pgdat; unsigned long reserve_pages = 0; - enum zone_type i, j; + enum zone_type i; for_each_online_pgdat(pgdat) { for (i = 0; i < MAX_NR_ZONES; i++) { struct zone *zone = pgdat->node_zones + i; - unsigned long max = 0; - - /* Find valid and maximum lowmem_reserve in the zone */ - for (j = i; j < MAX_NR_ZONES; j++) { - if (zone->lowmem_reserve[j] > max) - max = zone->lowmem_reserve[j]; - } + unsigned long max; /* we treat pages_high as reserved pages. */ - max += zone->pages_high; + max = calculate_max_lowmem_reserve(zone, i) + \ + zone->pages_high; if (max > zone->present_pages) max = zone->present_pages; @@ -2868,6 +2882,9 @@ static void setup_per_zone_lowmem_reserv struct pglist_data *pgdat; enum zone_type j, idx; + if (SINGLE_ZONE) + return; + for_each_online_pgdat(pgdat) { for (j = 0; j < MAX_NR_ZONES; j++) { struct zone *zone = pgdat->node_zones + j; @@ -3044,6 +3061,7 @@ int sysctl_min_slab_ratio_sysctl_handler } #endif +#if MULTI_ZONE /* * lowmem_reserve_ratio_sysctl_handler - just a wrapper around * proc_dointvec() so that we can call setup_per_zone_lowmem_reserve() @@ -3060,6 +3078,7 @@ int lowmem_reserve_ratio_sysctl_handler( setup_per_zone_lowmem_reserve(); return 0; } +#endif /* * percpu_pagelist_fraction - changes the pcp->high for each zone on each Index: linux-2.6.19-rc1-mm1/kernel/sysctl.c =================================================================== --- linux-2.6.19-rc1-mm1.orig/kernel/sysctl.c 2006-10-17 13:07:50.906590841 -0500 +++ linux-2.6.19-rc1-mm1/kernel/sysctl.c 2006-10-17 13:08:06.281925057 -0500 @@ -900,6 +900,7 @@ static ctl_table vm_table[] = { .proc_handler = &proc_dointvec, }, #endif +#if MULTI_ZONE { .ctl_name = VM_LOWMEM_RESERVE_RATIO, .procname = "lowmem_reserve_ratio", @@ -909,6 +910,7 @@ static ctl_table vm_table[] = { .proc_handler = &lowmem_reserve_ratio_sysctl_handler, .strategy = &sysctl_intvec, }, +#endif { .ctl_name = VM_DROP_PAGECACHE, .procname = "drop_caches", Index: linux-2.6.19-rc1-mm1/include/linux/mmzone.h =================================================================== --- linux-2.6.19-rc1-mm1.orig/include/linux/mmzone.h 2006-10-17 13:07:50.917333945 -0500 +++ linux-2.6.19-rc1-mm1/include/linux/mmzone.h 2007-04-02 23:35:55.689289129 -0500 @@ -171,6 +171,9 @@ enum zone_type { #endif #undef __ZONE_COUNT +#define MULTI_ZONE (ZONES_SHIFT > 0) +#define SINGLE_ZONE (ZONES_SHIFT == 0) + struct zone { /* Fields commonly accessed by the page allocator */ unsigned long free_pages; @@ -183,7 +186,7 @@ struct zone { * on the higher zones). This array is recalculated at runtime if the * sysctl_lowmem_reserve_ratio sysctl changes. */ - unsigned long lowmem_reserve[MAX_NR_ZONES]; + unsigned long lowmem_reserve[MAX_NR_ZONES - SINGLE_ZONE]; #ifdef CONFIG_NUMA int node; @@ -420,11 +423,11 @@ unsigned long __init node_memmap_size_by /* * zone_idx() returns 0 for the ZONE_DMA zone, 1 for the ZONE_NORMAL zone, etc. */ -#define zone_idx(zone) ((zone) - (zone)->zone_pgdat->node_zones) +#define zone_idx(zone) (MULTI_ZONE * ((zone) - (zone)->zone_pgdat->node_zones)) static inline int populated_zone(struct zone *zone) { - return (!!zone->present_pages); + return SINGLE_ZONE || (!!zone->present_pages); } static inline int is_highmem_idx(enum zone_type idx) @@ -438,7 +441,7 @@ static inline int is_highmem_idx(enum zo static inline int is_normal_idx(enum zone_type idx) { - return (idx == ZONE_NORMAL); + return SINGLE_ZONE || (idx == ZONE_NORMAL); } /** @@ -458,7 +461,8 @@ static inline int is_highmem(struct zone static inline int is_normal(struct zone *zone) { - return zone == zone->zone_pgdat->node_zones + ZONE_NORMAL; + return SINGLE_ZONE || + zone == zone->zone_pgdat->node_zones + ZONE_NORMAL; } static inline int is_dma32(struct zone *zone)