From: Ye Bin <yebin10@xxxxxxxxxx> Add instructions for 'drop_fs_caches sysctl' sysctl in 'vm.rst'. Signed-off-by: Ye Bin <yebin10@xxxxxxxxxx> --- Documentation/admin-guide/sysctl/vm.rst | 27 +++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/Documentation/admin-guide/sysctl/vm.rst b/Documentation/admin-guide/sysctl/vm.rst index f48eaa98d22d..4648ac1ac66c 100644 --- a/Documentation/admin-guide/sysctl/vm.rst +++ b/Documentation/admin-guide/sysctl/vm.rst @@ -36,6 +36,7 @@ Currently, these files are in /proc/sys/vm: - dirtytime_expire_seconds - dirty_writeback_centisecs - drop_caches +- drop_fs_caches - enable_soft_offline - extfrag_threshold - highmem_is_dirtyable @@ -268,6 +269,32 @@ used:: These are informational only. They do not mean that anything is wrong with your system. To disable them, echo 4 (bit 2) into drop_caches. +drop_fs_caches +============== + +Writing to this will cause the kernel to drop clean for a specific file system +caches, as well as reclaimable slab objects like dentries and inodes. Once +dropped, their memory becomes free. Except for specifying the device number for +a specific file system, everything else is consistent with drop_caches. The +device number can be viewed through "cat /proc/self/montinfo" or 'lsblk'. + +To free pagecache:: + + echo "MAJOR:MINOR:1" > /proc/sys/vm/drop_caches + +To free reclaimable slab objects (includes dentries and inodes):: + + echo "MAJOR:MINOR:2" > /proc/sys/vm/drop_caches + +To free slab objects and pagecache:: + + echo "MAJOR:MINOR:3" > /proc/sys/vm/drop_caches + +You may see informational messages in your kernel log when this file is +used:: + + echo (1234): drop_fs_caches: MAJOR:MINOR:3 + enable_soft_offline =================== Correctable memory errors are very common on servers. Soft-offline is kernel's -- 2.31.1
