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    SubjectRe: [PATCH RFC 0/7] rcu: v2 Inlinable preemptible rcu_read_lock() and rcu_read_unlock()
    On Sat, Apr 14, 2012 at 10:08:54AM -0700, Linus Torvalds wrote:
    > On Sat, Apr 14, 2012 at 9:58 AM, Linus Torvalds
    > <> wrote:
    > >
    > > I'll see if it boots and what it does to my profiles and
    > > microbenchmark, though.
    > Ok, I can't see any performance difference in the numbers - my
    > benchmark noise is *much* bigger than anything this would show.

    Might still be worthwhile on embedded CPUs that don't optimize
    function calls as thoroughly as does x86, maybe?

    > The profile looks fine, and obviously __rcu_read_lock() is entirely
    > gone. The top user (avc_has_perm_flags()) looks fine. I note that you
    > might want to look at the placement of the percpu data - I think it
    > probably makes sense to put the RCU data close to 'current' etc to get
    > as much cacheline sharing as possible, and it doesn't seem to be right
    > now, but it looks reasonable.

    Is there somewhere in non-architecture-specific code that would be a
    good place to put this? Or is the DEFINE_PER_CPU() for current_task
    moving from arch/x86 to core code?

    > But on the whole, I can't claim that it looks noticeable ;*(

    Well, then, I guess I don't feel quite so bad about having prioritized
    this so low for so long. ;-)

    Thanx, Paul

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