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Re: [PATCH] ipc/msg: Implement lockless pipelined wakeups

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Hi Sebastian,

On 10/30/2015 12:26 PM, Sebastian Andrzej Siewior wrote:
> This patch moves the wakeup_process() invocation so it is not done under
> the perm->lock by making use of a lockless wake_q. With this change, the
> waiter is woken up once the message has been assigned and it does not
> need to loop on SMP if the message points to NULL. In the signal case we
> still need to check the pointer under the lock to verify the state.
>
> This change should also avoid the introduction of preempt_disable() in
> -RT which avoids a busy-loop which pools for the NULL -> !NULL
> change if the waiter has a higher priority compared to the waker.
with regards to functional tests:
fakeroot is a heavy system V user (at least if it is configured for sysv).
"make -j" under fakeroot was a useful stresstest

with regards to benchmarks:
I've attached one of my files.

Otherwise: Nice!

--
     Manfred

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[PATCH] ipc/msg: Implement lockless pipelined wakeups Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2015-10-30 12:30 +0100
  Re: [PATCH] ipc/msg: Implement lockless pipelined wakeups "George Spelvin" <linux@horizon.com> - 2015-10-30 23:40 +0100
    Re: [PATCH] ipc/msg: Implement lockless pipelined wakeups Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2015-11-03 15:10 +0100
  Re: [PATCH] ipc/msg: Implement lockless pipelined wakeups Thomas Gleixner <tglx@linutronix.de> - 2015-10-31 11:40 +0100
    Re: [PATCH] ipc/msg: Implement lockless pipelined wakeups "George Spelvin" <linux@horizon.com> - 2015-10-31 14:10 +0100
      Re: [PATCH] ipc/msg: Implement lockless pipelined wakeups Thomas Gleixner <tglx@linutronix.de> - 2015-10-31 16:20 +0100
      Re: [PATCH] ipc/msg: Implement lockless pipelined wakeups Davidlohr Bueso <dave@stgolabs.net> - 2015-10-31 20:00 +0100
        Re: [PATCH] ipc/msg: Implement lockless pipelined wakeups Davidlohr Bueso <dave@stgolabs.net> - 2015-10-31 20:10 +0100
          Re: [PATCH] ipc/msg: Implement lockless pipelined wakeups Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2015-11-03 15:20 +0100
        Re: [PATCH] ipc/msg: Implement lockless pipelined wakeups Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2015-11-03 15:20 +0100
  Re: [PATCH] ipc/msg: Implement lockless pipelined wakeups Manfred Spraul <manfred@colorfullife.com> - 2015-11-01 05:40 +0100
    Re: [PATCH] ipc/msg: Implement lockless pipelined wakeups Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2015-11-03 16:00 +0100

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