Messages in this thread | | | Date | Thu, 22 Dec 2011 09:17:57 +0100 | From | Andi Kleen <> | Subject | Re: [PATCH] VFS: br_write_lock locks on possible CPUs other than online CPUs |
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On Thu, Dec 22, 2011 at 08:08:56AM +0000, Al Viro wrote: > On Wed, Dec 21, 2011 at 11:20:47PM -0800, Andrew Morton wrote: > > On Thu, 22 Dec 2011 07:02:15 +0000 Al Viro <viro@ZenIV.linux.org.uk> wrote: > > > > > On Wed, Dec 21, 2011 at 02:12:29PM -0800, Andrew Morton wrote: > > > > off-topic, but the lockdep stuff in include/linux/lglock.h > > > > (LOCKDEP_INIT_MAP and DEFINE_LGLOCK_LOCKDEP) appears to be dead code. > > > > > > Um? See ..._lock_init(); it's used there. > > > > oops, I had Andi's patch applied. > > > > Wanna take a look at it while things are fresh in your mind? > > a) tons of trivial conflicts with fs/namespace.c changes in my tree > b) more seriously, the question of overhead - see the mail you replied > to. >
The costly operations here are the atomics and nothing really changes for them. So I don't expect any measurable difference.
I actually have an idea to remove them for the common case, but not in that patchkit or cycle :)
I can run a ftrace if you want, but I expect any difference to be below the measurement inaccuracy.
-Andi
-- ak@linux.intel.com -- Speaking for myself only.
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