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authorGlauber Costa <glommer@parallels.com>2012-12-19 02:23:05 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2012-12-19 03:02:14 +0400
commit107dab5c92d5f9c3afe962036e47c207363255c7 (patch)
tree17722e888fc00428ef1614a097bae82d1e9de87a /include/linux
parent943a451a87d229ca564a27274b58eaeae35fde5d (diff)
downloadlinux-107dab5c92d5f9c3afe962036e47c207363255c7.tar.xz
slub: slub-specific propagation changes
SLUB allows us to tune a particular cache behavior with sysfs-based tunables. When creating a new memcg cache copy, we'd like to preserve any tunables the parent cache already had. This can be done by tapping into the store attribute function provided by the allocator. We of course don't need to mess with read-only fields. Since the attributes can have multiple types and are stored internally by sysfs, the best strategy is to issue a ->show() in the root cache, and then ->store() in the memcg cache. The drawback of that, is that sysfs can allocate up to a page in buffering for show(), that we are likely not to need, but also can't guarantee. To avoid always allocating a page for that, we can update the caches at store time with the maximum attribute size ever stored to the root cache. We will then get a buffer big enough to hold it. The corolary to this, is that if no stores happened, nothing will be propagated. It can also happen that a root cache has its tunables updated during normal system operation. In this case, we will propagate the change to all caches that are already active. [akpm@linux-foundation.org: tweak code to avoid __maybe_unused] Signed-off-by: Glauber Costa <glommer@parallels.com> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Frederic Weisbecker <fweisbec@redhat.com> Cc: Greg Thelen <gthelen@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: JoonSoo Kim <js1304@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Michal Hocko <mhocko@suse.cz> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Cc: Rik van Riel <riel@redhat.com> Cc: Suleiman Souhlal <suleiman@google.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux')
-rw-r--r--include/linux/slub_def.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index 364ba6c9fe21..9db4825cd393 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -103,6 +103,7 @@ struct kmem_cache {
#endif
#ifdef CONFIG_MEMCG_KMEM
struct memcg_cache_params *memcg_params;
+ int max_attr_size; /* for propagation, maximum size of a stored attr */
#endif
#ifdef CONFIG_NUMA