diff options
| -rw-r--r-- | Documentation/filesystems/proc.txt | 15 | ||||
| -rw-r--r-- | Documentation/sysctl/vm.txt | 7 | ||||
| -rw-r--r-- | include/linux/writeback.h | 1 | ||||
| -rw-r--r-- | kernel/sysctl.c | 18 | ||||
| -rw-r--r-- | mm/page-writeback.c | 11 |
5 files changed, 47 insertions, 5 deletions
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index 0b1b0c008613..07231afca72d 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -1315,6 +1315,21 @@ for writeout by the pdflush daemons. It is expressed in 100'ths of a second. Data which has been dirty in-memory for longer than this interval will be written out next time a pdflush daemon wakes up. +highmem_is_dirtyable +-------------------- + +Only present if CONFIG_HIGHMEM is set. + +This defaults to 0 (false), meaning that the ratios set above are calculated +as a percentage of lowmem only. This protects against excessive scanning +in page reclaim, swapping and general VM distress. + +Setting this to 1 can be useful on 32 bit machines where you want to make +random changes within an MMAPed file that is larger than your available +lowmem without causing large quantities of random IO. Is is safe if the +behavior of all programs running on the machine is known and memory will +not be otherwise stressed. + legacy_va_layout ---------------- diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt index 6f31f0a247d0..24eac1bc735d 100644 --- a/Documentation/sysctl/vm.txt +++ b/Documentation/sysctl/vm.txt @@ -22,6 +22,7 @@ Currently, these files are in /proc/sys/vm: - dirty_background_ratio - dirty_expire_centisecs - dirty_writeback_centisecs +- highmem_is_dirtyable (only if CONFIG_HIGHMEM set) - max_map_count - min_free_kbytes - laptop_mode @@ -40,9 +41,9 @@ Currently, these files are in /proc/sys/vm: ============================================================== dirty_ratio, dirty_background_ratio, dirty_expire_centisecs, -dirty_writeback_centisecs, vfs_cache_pressure, laptop_mode, -block_dump, swap_token_timeout, drop-caches, -hugepages_treat_as_movable: +dirty_writeback_centisecs, highmem_is_dirtyable, +vfs_cache_pressure, laptop_mode, block_dump, swap_token_timeout, +drop-caches, hugepages_treat_as_movable: See Documentation/filesystems/proc.txt diff --git a/include/linux/writeback.h b/include/linux/writeback.h index c6148bbf1250..b2cd826a8c90 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -100,6 +100,7 @@ extern int dirty_background_ratio; extern int vm_dirty_ratio; extern int dirty_writeback_interval; extern int dirty_expire_interval; +extern int vm_highmem_is_dirtyable; extern int block_dump; extern int laptop_mode; diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 7cb1ac3e6fff..d0b47b859067 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -84,8 +84,11 @@ extern int sysctl_stat_interval; extern int latencytop_enabled; /* Constants used for minimum and maximum */ -#ifdef CONFIG_DETECT_SOFTLOCKUP +#if defined(CONFIG_DETECT_SOFTLOCKUP) || defined(CONFIG_HIGHMEM) static int one = 1; +#endif + +#ifdef CONFIG_DETECT_SOFTLOCKUP static int sixty = 60; #endif @@ -1150,6 +1153,19 @@ static struct ctl_table vm_table[] = { .extra1 = &zero, }, #endif +#ifdef CONFIG_HIGHMEM + { + .ctl_name = CTL_UNNUMBERED, + .procname = "highmem_is_dirtyable", + .data = &vm_highmem_is_dirtyable, + .maxlen = sizeof(vm_highmem_is_dirtyable), + .mode = 0644, + .proc_handler = &proc_dointvec_minmax, + .strategy = &sysctl_intvec, + .extra1 = &zero, + .extra2 = &one, + }, +#endif /* * NOTE: do not add new entries to this table unless you have read * Documentation/sysctl/ctl_unnumbered.txt diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 8137482abd6e..c689b60af000 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -69,6 +69,12 @@ static inline long sync_writeback_pages(void) int dirty_background_ratio = 5; /* + * free highmem will not be subtracted from the total free memory + * for calculating free ratios if vm_highmem_is_dirtyable is true + */ +int vm_highmem_is_dirtyable; + +/* * The generator of dirty data starts writeback at this percentage */ int vm_dirty_ratio = 10; @@ -287,7 +293,10 @@ static unsigned long determine_dirtyable_memory(void) x = global_page_state(NR_FREE_PAGES) + global_page_state(NR_INACTIVE) + global_page_state(NR_ACTIVE); - x -= highmem_dirtyable_memory(x); + + if (!vm_highmem_is_dirtyable) + x -= highmem_dirtyable_memory(x); + return x + 1; /* Ensure that we never return 0 */ } |