diff options
| -rw-r--r-- | Documentation/filesystems/proc.txt | 17 | ||||
| -rw-r--r-- | Documentation/sysctl/vm.txt | 3 | ||||
| -rw-r--r-- | fs/Makefile | 2 | ||||
| -rw-r--r-- | fs/drop_caches.c | 68 | ||||
| -rw-r--r-- | include/linux/mm.h | 7 | ||||
| -rw-r--r-- | include/linux/sysctl.h | 1 | ||||
| -rw-r--r-- | kernel/sysctl.c | 10 | ||||
| -rw-r--r-- | mm/truncate.c | 1 | ||||
| -rw-r--r-- | mm/vmscan.c | 3 |
9 files changed, 107 insertions, 5 deletions
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index d477356..a4dcf42 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -1302,6 +1302,23 @@ VM has token based thrashing control mechanism and uses the token to prevent unnecessary page faults in thrashing situation. The unit of the value is second. The value would be useful to tune thrashing behavior. +drop_caches +----------- + +Writing to this will cause the kernel to drop clean caches, dentries and +inodes from memory, causing that memory to become free. + +To free pagecache: + echo 1 > /proc/sys/vm/drop_caches +To free dentries and inodes: + echo 2 > /proc/sys/vm/drop_caches +To free pagecache, dentries and inodes: + echo 3 > /proc/sys/vm/drop_caches + +As this is a non-destructive operation and dirty objects are not freeable, the +user should run `sync' first. + + 2.5 /proc/sys/dev - Device specific parameters ---------------------------------------------- diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt index 2f1aae3..89ba1a4 100644 --- a/Documentation/sysctl/vm.txt +++ b/Documentation/sysctl/vm.txt @@ -26,12 +26,13 @@ Currently, these files are in /proc/sys/vm: - min_free_kbytes - laptop_mode - block_dump +- drop-caches ============================================================== dirty_ratio, dirty_background_ratio, dirty_expire_centisecs, dirty_writeback_centisecs, vfs_cache_pressure, laptop_mode, -block_dump, swap_token_timeout: +block_dump, swap_token_timeout, drop-caches: See Documentation/filesystems/proc.txt diff --git a/fs/Makefile b/fs/Makefile index 7367611..35e9aec 100644 --- a/fs/Makefile +++ b/fs/Makefile @@ -10,7 +10,7 @@ obj-y := open.o read_write.o file_table.o buffer.o bio.o super.o \ ioctl.o readdir.o select.o fifo.o locks.o dcache.o inode.o \ attr.o bad_inode.o file.o filesystems.o namespace.o aio.o \ seq_file.o xattr.o libfs.o fs-writeback.o mpage.o direct-io.o \ - ioprio.o pnode.o + ioprio.o pnode.o drop_caches.o obj-$(CONFIG_INOTIFY) += inotify.o obj-$(CONFIG_EPOLL) += eventpoll.o diff --git a/fs/drop_caches.c b/fs/drop_caches.c new file mode 100644 index 0000000..4e47623 --- /dev/null +++ b/fs/drop_caches.c @@ -0,0 +1,68 @@ +/* + * Implement the manual drop-all-pagecache function + */ + +#include <linux/kernel.h> +#include <linux/mm.h> +#include <linux/fs.h> +#include <linux/writeback.h> +#include <linux/sysctl.h> +#include <linux/gfp.h> + +/* A global variable is a bit ugly, but it keeps the code simple */ +int sysctl_drop_caches; + +static void drop_pagecache_sb(struct super_block *sb) +{ + struct inode *inode; + + spin_lock(&inode_lock); + list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { + if (inode->i_state & (I_FREEING|I_WILL_FREE)) + continue; + invalidate_inode_pages(inode->i_mapping); + } + spin_unlock(&inode_lock); +} + +void drop_pagecache(void) +{ + struct super_block *sb; + + spin_lock(&sb_lock); +restart: + list_for_each_entry(sb, &super_blocks, s_list) { + sb->s_count++; + spin_unlock(&sb_lock); + down_read(&sb->s_umount); + if (sb->s_root) + drop_pagecache_sb(sb); + up_read(&sb->s_umount); + spin_lock(&sb_lock); + if (__put_super_and_need_restart(sb)) + goto restart; + } + spin_unlock(&sb_lock); +} + +void drop_slab(void) +{ + int nr_objects; + + do { + nr_objects = shrink_slab(1000, GFP_KERNEL, 1000); + } while (nr_objects > 10); +} + +int drop_caches_sysctl_handler(ctl_table *table, int write, + struct file *file, void __user *buffer, size_t *length, loff_t *ppos) +{ + proc_dointvec_minmax(table, write, file, buffer, length, ppos); + if (write) { + if (sysctl_drop_caches & 1) + drop_pagecache(); + if (sysctl_drop_caches & 2) + drop_slab(); + } + return 0; +} diff --git a/include/linux/mm.h b/include/linux/mm.h index bc01fff..83c651f 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1036,5 +1036,12 @@ int in_gate_area_no_task(unsigned long addr); /* /proc/<pid>/oom_adj set to -17 protects from the oom-killer */ #define OOM_DISABLE -17 +int drop_caches_sysctl_handler(struct ctl_table *, int, struct file *, + void __user *, size_t *, loff_t *); +int shrink_slab(unsigned long scanned, gfp_t gfp_mask, + unsigned long lru_pages); +void drop_pagecache(void); +void drop_slab(void); + #endif /* __KERNEL__ */ #endif /* _LINUX_MM_H */ diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h index a9b80fc..4cd267f 100644 --- a/include/linux/sysctl.h +++ b/include/linux/sysctl.h @@ -180,6 +180,7 @@ enum VM_VFS_CACHE_PRESSURE=26, /* dcache/icache reclaim pressure */ VM_LEGACY_VA_LAYOUT=27, /* legacy/compatibility virtual address space layout */ VM_SWAP_TOKEN_TIMEOUT=28, /* default time for token time out */ + VM_DROP_PAGECACHE=29, /* int: nuke lots of pagecache */ }; diff --git a/kernel/sysctl.c b/kernel/sysctl.c index a85047b..8dcf6fd 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -68,6 +68,7 @@ extern int min_free_kbytes; extern int printk_ratelimit_jiffies; extern int printk_ratelimit_burst; extern int pid_max_min, pid_max_max; +extern int sysctl_drop_caches; #if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_X86) int unknown_nmi_panic; @@ -775,6 +776,15 @@ static ctl_table vm_table[] = { .strategy = &sysctl_intvec, }, { + .ctl_name = VM_DROP_PAGECACHE, + .procname = "drop_caches", + .data = &sysctl_drop_caches, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = drop_caches_sysctl_handler, + .strategy = &sysctl_intvec, + }, + { .ctl_name = VM_MIN_FREE_KBYTES, .procname = "min_free_kbytes", .data = &min_free_kbytes, diff --git a/mm/truncate.c b/mm/truncate.c index 7dee327..b1a463d 100644 --- a/mm/truncate.c +++ b/mm/truncate.c @@ -249,7 +249,6 @@ unlock: break; } pagevec_release(&pvec); - cond_resched(); } return ret; } diff --git a/mm/vmscan.c b/mm/vmscan.c index be8235f..428c580 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -180,8 +180,7 @@ EXPORT_SYMBOL(remove_shrinker); * * Returns the number of slab objects which we shrunk. */ -static int shrink_slab(unsigned long scanned, gfp_t gfp_mask, - unsigned long lru_pages) +int shrink_slab(unsigned long scanned, gfp_t gfp_mask, unsigned long lru_pages) { struct shrinker *shrinker; int ret = 0; |
