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authorAndy Lutomirski <luto@kernel.org>2016-09-16 08:45:48 +0300
committerIngo Molnar <mingo@kernel.org>2016-09-16 10:18:54 +0300
commit68f24b08ee892d47bdef925d676e1ae1ccc316f8 (patch)
treeeb68202da134522dd22c4bf78487ae9017df970f /include/linux/init_task.h
parentaa1f1a639621672b68f654dc815a7d8298ff396f (diff)
downloadlinux-68f24b08ee892d47bdef925d676e1ae1ccc316f8.tar.xz
sched/core: Free the stack early if CONFIG_THREAD_INFO_IN_TASK
We currently keep every task's stack around until the task_struct itself is freed. This means that we keep the stack allocation alive for longer than necessary and that, under load, we free stacks in big batches whenever RCU drops the last task reference. Neither of these is good for reuse of cache-hot memory, and freeing in batches prevents us from usefully caching small numbers of vmalloced stacks. On architectures that have thread_info on the stack, we can't easily change this, but on architectures that set THREAD_INFO_IN_TASK, we can free it as soon as the task is dead. Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Jann Horn <jann@thejh.net> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/08ca06cde00ebed0046c5d26cbbf3fbb7ef5b812.1474003868.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/linux/init_task.h')
-rw-r--r--include/linux/init_task.h4
1 files changed, 3 insertions, 1 deletions
diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index 9c04d44eeb3c..325f649d77ff 100644
--- a/include/linux/init_task.h
+++ b/include/linux/init_task.h
@@ -186,7 +186,9 @@ extern struct task_group root_task_group;
#endif
#ifdef CONFIG_THREAD_INFO_IN_TASK
-# define INIT_TASK_TI(tsk) .thread_info = INIT_THREAD_INFO(tsk),
+# define INIT_TASK_TI(tsk) \
+ .thread_info = INIT_THREAD_INFO(tsk), \
+ .stack_refcount = ATOMIC_INIT(1),
#else
# define INIT_TASK_TI(tsk)
#endif