Create a dynamically sized pool of threads for doing very slow work items
Create a dynamically sized pool of threads for doing very slow work items, such
as invoking mkdir() or rmdir() - things that may take a long time and may
sleep, holding mutexes/semaphores and hogging a thread, and are thus unsuitable
for workqueues.
The number of threads is always at least a settable minimum, but more are
started when there's more work to do, up to a limit. Because of the nature of
the load, it's not suitable for a 1-thread-per-CPU type pool. A system with
one CPU may well want several threads.
This is used by FS-Cache to do slow caching operations in the background, such
as looking up, creating or deleting cache objects.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
diff --git a/init/Kconfig b/init/Kconfig
index 1398a14..236a793 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1014,6 +1014,18 @@
source "arch/Kconfig"
+config SLOW_WORK
+ default n
+ bool "Enable slow work thread pool"
+ help
+ The slow work thread pool provides a number of dynamically allocated
+ threads that can be used by the kernel to perform operations that
+ take a relatively long time.
+
+ An example of this would be CacheFiles doing a path lookup followed
+ by a series of mkdirs and a create call, all of which have to touch
+ disk.
+
endmenu # General setup
config HAVE_GENERIC_DMA_COHERENT