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authorDave Chinner <dchinner@redhat.com>2011-07-08 14:14:45 +1000
committerAl Viro <viro@zeniv.linux.org.uk>2011-07-20 20:47:41 -0400
commit8ab47664d51a69ea79fe70bb07ca80664f74f76b (patch)
treea0cc73a909840edfb23b4b4490c39fd222cce0fa /Documentation/filesystems/vfs.txt
parent0e1fdafd93980eac62e778798549ce0f6073905c (diff)
vfs: increase shrinker batch size
Now that the per-sb shrinker is responsible for shrinking 2 or more caches, increase the batch size to keep econmies of scale for shrinking each cache. Increase the shrinker batch size to 1024 objects. To allow for a large increase in batch size, add a conditional reschedule to prune_icache_sb() so that we don't hold the LRU spin lock for too long. This mirrors the behaviour of the __shrink_dcache_sb(), and allows us to increase the batch size without needing to worry about problems caused by long lock hold times. To ensure that filesystems using the per-sb shrinker callouts don't cause problems, document that the object freeing method must reschedule appropriately inside loops. Signed-off-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'Documentation/filesystems/vfs.txt')
-rw-r--r--Documentation/filesystems/vfs.txt6
1 files changed, 6 insertions, 0 deletions
diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
index fd24f34f120..6bf85b78cfe 100644
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -317,6 +317,12 @@ or bottom half).
the VM is trying to reclaim under GFP_NOFS conditions, hence this
method does not need to handle that situation itself.
+ Implementations must include conditional reschedule calls inside any
+ scanning loop that is done. This allows the VFS to determine
+ appropriate scan batch sizes without having to worry about whether
+ implementations will cause holdoff problems due to large scan batch
+ sizes.
+
Whoever sets up the inode is responsible for filling in the "i_op" field. This
is a pointer to a "struct inode_operations" which describes the methods that
can be performed on individual inodes.