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Subject: Re: [PATCH 08/35] autonuma: introduce kthread_bind_node()
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Tue, 29 May 2012 19:48:06 +0200
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To: Andrea Arcangeli <aarcange@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Hillf Danton <dhillf@gmail.com>, Dan Smith <danms@us.ibm.com>, Linus Torvalds <torvalds@linux-foundation.org>, Andrew Morton <akpm@linux-foundation.org>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>, Paul Turner <pjt@google.com>, Suresh Siddha <suresh.b.siddha@intel.com>, Mike Galbraith <efault@gmx.de>, "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>, Lai Jiangshan <laijs@cn.fujitsu.com>, Bharata B Rao <bharata.rao@gmail.com>, Lee Schermerhorn <Lee.Schermerhorn@hp.com>, Rik van Riel <riel@redhat.com>, Johannes Weiner <hannes@cmpxchg.org>, Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>, Christoph Lameter <cl@linux.com>

On Tue, 2012-05-29 at 19:44 +0200, Andrea Arcangeli wrote:
>=20
> But it'd be totally bad not to do the hard bindings to the cpu_s_ of
> the node, and not using PF_THREAD_BOUND would just allow userland to
> shoot itself in the foot. I mean if PF_THREAD_BOUND wouldn't exist
> already I wouldn't add it, but considering somebody bothered to
> implement it for the sake to make userland root user "safer", it'd be
> really silly not to take advantage of that for knuma_migrated too
> (even if it binds to more than 1 CPU).=20

No, I'm absolutely ok with the user shooting himself in the foot. The
thing exists because you can crash stuff if you get it wrong with
per-cpu.

Crashing is not good, worse performance is his own damn fault.

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