The patch titled
Mark rwsem functions as __sched for wchan/profiling
has been added to the -mm tree. Its filename is
mark-rwsem-functions-as-__sched-for-wchan-profiling.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: Mark rwsem functions as __sched for wchan/profiling
From: Livio Soares <livio@xxxxxxxxxxxxxxxx>
This following commit
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=fdf8cb0909b531f9ae8f9b9d7e4eb35ba3505f07
un-inlined a low-level rwsem function, but did not mark it as __sched. The
result is that it now shows up as thread wchan (which also affects
/proc/profile stats). The following simple patch fixes this by properly
marking rwsem_down_failed_common() as a __sched function.
Also in this patch, which is up for discussion, marks down_read() and
down_write() proper as __sched. For profiling, it is pretty much useless
to know that a semaphore is beig help - it is necessary to know _which_
one. By going up another frame on the stack, the information becomes much
more useful.
In summary, the below change to lib/rwsem.c should be applied; the changes
to kernel/rwsem.c could be applied if other kernel hackers agree with my
proposal that down_read()/down_write() in the profile is not enough.
Signed-off-by: Livio Soares <livio@xxxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/rwsem.c | 4 ++--
lib/rwsem.c | 2 +-
2 files changed, 3 insertions(+), 3 deletions(-)
diff -puN kernel/rwsem.c~mark-rwsem-functions-as-__sched-for-wchan-profiling kernel/rwsem.c
--- a/kernel/rwsem.c~mark-rwsem-functions-as-__sched-for-wchan-profiling
+++ a/kernel/rwsem.c
@@ -15,7 +15,7 @@
/*
* lock for reading
*/
-void down_read(struct rw_semaphore *sem)
+void __sched down_read(struct rw_semaphore *sem)
{
might_sleep();
rwsem_acquire_read(&sem->dep_map, 0, 0, _RET_IP_);
@@ -42,7 +42,7 @@ EXPORT_SYMBOL(down_read_trylock);
/*
* lock for writing
*/
-void down_write(struct rw_semaphore *sem)
+void __sched down_write(struct rw_semaphore *sem)
{
might_sleep();
rwsem_acquire(&sem->dep_map, 0, 0, _RET_IP_);
diff -puN lib/rwsem.c~mark-rwsem-functions-as-__sched-for-wchan-profiling lib/rwsem.c
--- a/lib/rwsem.c~mark-rwsem-functions-as-__sched-for-wchan-profiling
+++ a/lib/rwsem.c
@@ -146,7 +146,7 @@ __rwsem_do_wake(struct rw_semaphore *sem
/*
* wait for a lock to be granted
*/
-static struct rw_semaphore *
+static struct rw_semaphore __sched *
rwsem_down_failed_common(struct rw_semaphore *sem,
struct rwsem_waiter *waiter, signed long adjustment)
{
_
Patches currently in -mm which might be from livio@xxxxxxxxxxxxxxxx are
mark-rwsem-functions-as-__sched-for-wchan-profiling.patch
-
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