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Date: Tue, 20 Oct 2015 11:15:07 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Ling Ma <ling.ma.program@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>, mingo@redhat.com,
        linux-kernel@vger.kernel.org, Ma Ling <ling.ml@alibaba-inc.com>,
        Waiman.Long@hpe.com
Subject: Re: [RFC PATCH] qspinlock: Improve performance by reducing load
 instruction rollback
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On Tue, Oct 20, 2015 at 10:57:53AM +0800, Ling Ma wrote:
> >
> > So it would be nice to create a new user-space spinlock testing facility, via a
> > new 'perf bench spinlock' feature or so. That way others can test and validate
> > your results on different hardware as well.
> >
> Attached the spinlock test module . Queued spinlock will run very
> slowly in user space
> because process switch context, it is OK for  spinlock-test
> implementation with kernel module ?

Works just fine in userspace if you pin each thread to a cpu and ensure
there's nothing else running on the system.