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Date: Tue, 1 Aug 2017 06:23:09 -0700
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Nicholas Piggin <npiggin@gmail.com>,
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Subject: Re: [RFC PATCH v2] membarrier: expedited private command
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On Tue, Aug 01, 2017 at 12:22:03PM +0200, Peter Zijlstra wrote:

[ . . . ]

> As to scheduler IPIs, those are limited to the CPUs the user is limited
> to and are rate limited by the wakeup-latency of the tasks. After all,
> all the time a task is runnable but not running, wakeups are no-ops.

Can't that wakeup-latency limitation be overcome by a normal user simply
by having lots of tasks to wake up, which then go back to sleep almost
immediately?  Coupled with very a low-priority CPU-bound task on each CPU?

							Thanx, Paul