Message-ID: <55B66C0E.5050504@hp.com>
Date: Mon, 27 Jul 2015 13:36:14 -0400
From: Waiman Long <waiman.long@hp.com>
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To: Davidlohr Bueso <dave@stgolabs.net>
CC: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>, "H. Peter Anvin" <hpa@zytor.com>,
        x86@kernel.org, linux-kernel@vger.kernel.org,
        Scott J Norton <scott.norton@hp.com>,
        Douglas Hatch <doug.hatch@hp.com>
Subject: Re: [PATCH v3 0/7] locking/qspinlock: Enhance pvqspinlock performance
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On 07/26/2015 09:18 PM, Davidlohr Bueso wrote:
> On Wed, 2015-07-22 at 16:12 -0400, Waiman Long wrote:
>> Patch 3 allows the collection of various count data that are useful
>> to see what is happening in the system. They do add a bit of overhead
>> when enabled slowing performance a tiny bit.
> Ah ok you do mention the overhead. Hmmm but what's a tiny bit? A kernel
> build comparison would be pretty nice to have a "usability" view.
>
> Thanks,
> Davidlohr
>

You will probably see a few seconds of slowdown for a kernel build that 
took 3 mins. So it is about a few percents and it varies a bit from run 
to run.

Cheers,
Longman
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