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Subject: Re: [PATCH] x86,switch_mm: skip atomic operations for init_mm
From: Mike Galbraith <efault@gmx.de>
To: Andy Lutomirski <luto@kernel.org>, riel@surriel.com
Cc: LKML <linux-kernel@vger.kernel.org>, songliubraving@fb.com,
        kernel-team <kernel-team@fb.com>, Ingo Molnar <mingo@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>, X86 ML <x86@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>
Date: Sat, 02 Jun 2018 05:39:36 +0200
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On Fri, 2018-06-01 at 13:03 -0700, Andy Lutomirski wrote:
> 
> Mike, you never did say: do you have PCID on your CPU?

Yes.

>   Also, what is
> your workload doing to cause so many switches back and forth between
> init_mm and a task.

pipe-test measures pipe round trip, does nearly nothing but schedule.  

	-Mike