Loading Documentation/sysctl/vm.txt +16 −0 Original line number Diff line number Diff line Loading @@ -29,6 +29,7 @@ Currently, these files are in /proc/sys/vm: - dirty_writeback_centisecs - drop_caches - extfrag_threshold - extra_free_kbytes - hugepages_treat_as_movable - hugetlb_shm_group - laptop_mode Loading Loading @@ -198,6 +199,21 @@ fragmentation index is <= extfrag_threshold. The default value is 500. ============================================================== extra_free_kbytes This parameter tells the VM to keep extra free memory between the threshold where background reclaim (kswapd) kicks in, and the threshold where direct reclaim (by allocating processes) kicks in. This is useful for workloads that require low latency memory allocations and have a bounded burstiness in memory allocations, for example a realtime application that receives and transmits network traffic (causing in-kernel memory allocations) with a maximum total message burst size of 200MB may need 200MB of extra free memory to avoid direct reclaim related latencies. ============================================================== hugepages_treat_as_movable This parameter is only useful when kernelcore= is specified at boot time to Loading kernel/sysctl.c +9 −0 Original line number Diff line number Diff line Loading @@ -105,6 +105,7 @@ extern char core_pattern[]; extern unsigned int core_pipe_limit; #endif extern int pid_max; extern int extra_free_kbytes; extern int min_free_order_shift; extern int pid_max_min, pid_max_max; extern int percpu_pagelist_fraction; Loading Loading @@ -1294,6 +1295,14 @@ static struct ctl_table vm_table[] = { .proc_handler = min_free_kbytes_sysctl_handler, .extra1 = &zero, }, { .procname = "extra_free_kbytes", .data = &extra_free_kbytes, .maxlen = sizeof(extra_free_kbytes), .mode = 0644, .proc_handler = min_free_kbytes_sysctl_handler, .extra1 = &zero, }, { .procname = "min_free_order_shift", .data = &min_free_order_shift, Loading mm/page_alloc.c +25 −7 Original line number Diff line number Diff line Loading @@ -203,9 +203,21 @@ static char * const zone_names[MAX_NR_ZONES] = { "Movable", }; /* * Try to keep at least this much lowmem free. Do not allow normal * allocations below this point, only high priority ones. Automatically * tuned according to the amount of memory in the system. */ int min_free_kbytes = 1024; int min_free_order_shift = 1; /* * Extra memory for the system to try freeing. Used to temporarily * free memory, to make space for new workloads. Anyone can allocate * down to the min watermarks controlled by min_free_kbytes above. */ int extra_free_kbytes; static unsigned long __meminitdata nr_kernel_pages; static unsigned long __meminitdata nr_all_pages; static unsigned long __meminitdata dma_reserve; Loading Loading @@ -5380,6 +5392,7 @@ static void setup_per_zone_lowmem_reserve(void) static void __setup_per_zone_wmarks(void) { unsigned long pages_min = min_free_kbytes >> (PAGE_SHIFT - 10); unsigned long pages_low = extra_free_kbytes >> (PAGE_SHIFT - 10); unsigned long lowmem_pages = 0; struct zone *zone; unsigned long flags; Loading @@ -5391,11 +5404,14 @@ static void __setup_per_zone_wmarks(void) } for_each_zone(zone) { u64 tmp; u64 min, low; spin_lock_irqsave(&zone->lock, flags); tmp = (u64)pages_min * zone->managed_pages; do_div(tmp, lowmem_pages); min = (u64)pages_min * zone->present_pages; do_div(min, lowmem_pages); low = (u64)pages_low * zone->present_pages; do_div(low, vm_total_pages); if (is_highmem(zone)) { /* * __GFP_HIGH and PF_MEMALLOC allocations usually don't Loading @@ -5416,11 +5432,13 @@ static void __setup_per_zone_wmarks(void) * If it's a lowmem zone, reserve a number of pages * proportionate to the zone's size. */ zone->watermark[WMARK_MIN] = tmp; zone->watermark[WMARK_MIN] = min; } zone->watermark[WMARK_LOW] = min_wmark_pages(zone) + (tmp >> 2); zone->watermark[WMARK_HIGH] = min_wmark_pages(zone) + (tmp >> 1); zone->watermark[WMARK_LOW] = min_wmark_pages(zone) + low + (min >> 2); zone->watermark[WMARK_HIGH] = min_wmark_pages(zone) + low + (min >> 1); setup_zone_migrate_reserve(zone); spin_unlock_irqrestore(&zone->lock, flags); Loading Loading @@ -5533,7 +5551,7 @@ module_init(init_per_zone_wmark_min) /* * min_free_kbytes_sysctl_handler - just a wrapper around proc_dointvec() so * that we can call two helper functions whenever min_free_kbytes * changes. * or extra_free_kbytes changes. */ int min_free_kbytes_sysctl_handler(ctl_table *table, int write, void __user *buffer, size_t *length, loff_t *ppos) Loading Loading
Documentation/sysctl/vm.txt +16 −0 Original line number Diff line number Diff line Loading @@ -29,6 +29,7 @@ Currently, these files are in /proc/sys/vm: - dirty_writeback_centisecs - drop_caches - extfrag_threshold - extra_free_kbytes - hugepages_treat_as_movable - hugetlb_shm_group - laptop_mode Loading Loading @@ -198,6 +199,21 @@ fragmentation index is <= extfrag_threshold. The default value is 500. ============================================================== extra_free_kbytes This parameter tells the VM to keep extra free memory between the threshold where background reclaim (kswapd) kicks in, and the threshold where direct reclaim (by allocating processes) kicks in. This is useful for workloads that require low latency memory allocations and have a bounded burstiness in memory allocations, for example a realtime application that receives and transmits network traffic (causing in-kernel memory allocations) with a maximum total message burst size of 200MB may need 200MB of extra free memory to avoid direct reclaim related latencies. ============================================================== hugepages_treat_as_movable This parameter is only useful when kernelcore= is specified at boot time to Loading
kernel/sysctl.c +9 −0 Original line number Diff line number Diff line Loading @@ -105,6 +105,7 @@ extern char core_pattern[]; extern unsigned int core_pipe_limit; #endif extern int pid_max; extern int extra_free_kbytes; extern int min_free_order_shift; extern int pid_max_min, pid_max_max; extern int percpu_pagelist_fraction; Loading Loading @@ -1294,6 +1295,14 @@ static struct ctl_table vm_table[] = { .proc_handler = min_free_kbytes_sysctl_handler, .extra1 = &zero, }, { .procname = "extra_free_kbytes", .data = &extra_free_kbytes, .maxlen = sizeof(extra_free_kbytes), .mode = 0644, .proc_handler = min_free_kbytes_sysctl_handler, .extra1 = &zero, }, { .procname = "min_free_order_shift", .data = &min_free_order_shift, Loading
mm/page_alloc.c +25 −7 Original line number Diff line number Diff line Loading @@ -203,9 +203,21 @@ static char * const zone_names[MAX_NR_ZONES] = { "Movable", }; /* * Try to keep at least this much lowmem free. Do not allow normal * allocations below this point, only high priority ones. Automatically * tuned according to the amount of memory in the system. */ int min_free_kbytes = 1024; int min_free_order_shift = 1; /* * Extra memory for the system to try freeing. Used to temporarily * free memory, to make space for new workloads. Anyone can allocate * down to the min watermarks controlled by min_free_kbytes above. */ int extra_free_kbytes; static unsigned long __meminitdata nr_kernel_pages; static unsigned long __meminitdata nr_all_pages; static unsigned long __meminitdata dma_reserve; Loading Loading @@ -5380,6 +5392,7 @@ static void setup_per_zone_lowmem_reserve(void) static void __setup_per_zone_wmarks(void) { unsigned long pages_min = min_free_kbytes >> (PAGE_SHIFT - 10); unsigned long pages_low = extra_free_kbytes >> (PAGE_SHIFT - 10); unsigned long lowmem_pages = 0; struct zone *zone; unsigned long flags; Loading @@ -5391,11 +5404,14 @@ static void __setup_per_zone_wmarks(void) } for_each_zone(zone) { u64 tmp; u64 min, low; spin_lock_irqsave(&zone->lock, flags); tmp = (u64)pages_min * zone->managed_pages; do_div(tmp, lowmem_pages); min = (u64)pages_min * zone->present_pages; do_div(min, lowmem_pages); low = (u64)pages_low * zone->present_pages; do_div(low, vm_total_pages); if (is_highmem(zone)) { /* * __GFP_HIGH and PF_MEMALLOC allocations usually don't Loading @@ -5416,11 +5432,13 @@ static void __setup_per_zone_wmarks(void) * If it's a lowmem zone, reserve a number of pages * proportionate to the zone's size. */ zone->watermark[WMARK_MIN] = tmp; zone->watermark[WMARK_MIN] = min; } zone->watermark[WMARK_LOW] = min_wmark_pages(zone) + (tmp >> 2); zone->watermark[WMARK_HIGH] = min_wmark_pages(zone) + (tmp >> 1); zone->watermark[WMARK_LOW] = min_wmark_pages(zone) + low + (min >> 2); zone->watermark[WMARK_HIGH] = min_wmark_pages(zone) + low + (min >> 1); setup_zone_migrate_reserve(zone); spin_unlock_irqrestore(&zone->lock, flags); Loading Loading @@ -5533,7 +5551,7 @@ module_init(init_per_zone_wmark_min) /* * min_free_kbytes_sysctl_handler - just a wrapper around proc_dointvec() so * that we can call two helper functions whenever min_free_kbytes * changes. * or extra_free_kbytes changes. */ int min_free_kbytes_sysctl_handler(ctl_table *table, int write, void __user *buffer, size_t *length, loff_t *ppos) Loading
