mm: dirty balancing for tasks

Based on ideas of Andrew:
  http://marc.info/?l=linux-kernel&m=102912915020543&w=2

Scale the bdi dirty limit inversly with the tasks dirty rate.
This makes heavy writers have a lower dirty limit than the occasional writer.

Andrea proposed something similar:
  http://lwn.net/Articles/152277/

The main disadvantage to his patch is that he uses an unrelated quantity to
measure time, which leaves him with a workload dependant tunable. Other than
that the two approaches appear quite similar.

[akpm@linux-foundation.org: fix warning]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 10 insertions, 0 deletions

diff --git a/kernel/fork.c b/kernel/fork.c
index 3fc3c1383912..163325af8179 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -107,6 +107,7 @@ static struct kmem_cache *mm_cachep;
 
 void free_task(struct task_struct *tsk)
 {
+        prop_local_destroy_single(&tsk->dirties);
         free_thread_info(tsk->stack);
         rt_mutex_debug_task_free(tsk);
         free_task_struct(tsk);
@@ -163,6 +164,7 @@ static struct task_struct *dup_task_struct(struct task_struct *orig)
 {
         struct task_struct *tsk;
         struct thread_info *ti;
+        int err;
 
         prepare_to_copy(orig);
 
@@ -178,6 +180,14 @@ static struct task_struct *dup_task_struct(struct task_struct *orig)
 
         *tsk = *orig;
         tsk->stack = ti;
+
+        err = prop_local_init_single(&tsk->dirties);
+        if (err) {
+                free_thread_info(ti);
+                free_task_struct(tsk);
+                return NULL;
+        }
+
         setup_thread_stack(tsk, orig);
 
 #ifdef CONFIG_CC_STACKPROTECTOR