From: "Emilio G. Cota" <cota@braap.org>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>,
"Richard Henderson" <rth@twiddle.net>,
"Laurent Vivier" <laurent@vivier.eu>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Alex Benn�e" <alex.bennee@linaro.org>,
qemu-devel <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] Benchmarking linux-user performance
Date: Fri, 10 Mar 2017 21:25:06 -0500 [thread overview]
Message-ID: <20170311022506.GB26530@flamenco> (raw)
In-Reply-To: <CAFEAcA9s0tHLYFwm+SP22ecB9uw1oyXdJSf5iG0iKzwRQuoGpQ@mail.gmail.com>
On Fri, Mar 10, 2017 at 12:48:31 +0100, Peter Maydell wrote:
> On 10 March 2017 at 12:45, Dr. David Alan Gilbert <dgilbert@redhat.com> wrote:
> > * Emilio G. Cota (cota@braap.org) wrote:
> >> x86_64 NBench Floating Point Performance
> >> Host: Intel(R) Xeon(R) CPU E5-2690 0 @ 2.90GHz
> >>
> >> 1.88 +-+-+---+--+---+---+---+--+---+---+---+---+--+---+---+---+--+---+-+-+
> >> | + + + *A*#*A* + + + + + + + + + + + + |
> >> 1.86 +-+ *** *** +-+
> >> | # # *A*#*** |
> >> | *A*# # # ## *A* |
> >> 1.84 +-+ # *A* *A* # +-+
> >> | # # *A* |
> >> 1.82 +-+ # # ## +-+
> >> | # *A*# # |
> >> 1.8 +-+ # # #*A* *A* +-+
> >> | # *A* # # |
> >> 1.78 +-+*A* # *A* # +-+
> >> | # ***# # # |
> >> | *A*#*A* # # |
> >> 1.76 +-+ *** # # +-+
> >> | + + + + + + + + + + + + + + *A* + + |
> >> 1.74 +-+-+---+--+---+---+---+--+---+---+---+---+--+---+---+---+--+---+-+-+
> >> v1.v1.v1.2v1.3v1.4v1.v1.6v1.7v2.0v2.1v2.v2.3v2.4v2.5v2.v2.7v2.8.0
> >> QEMU version
> >
> > I'm assuming the dips are where QEMU fixed something and cared about corner
> > cases/accuracy?
>
> Given the scale on the LHS is from 1.74 to 1.88 my guess is that the
> variation is in large part noise and the major thing is "our fp
> performance is bounded by softfloat, which doesn't change and is
> always very slow".
It isn't "measurement noise" -- if you look at the PNGs the measurements
are very stable (all points have error bars): http://imgur.com/a/nF7Ls
It's true that performance here varies very little. This is just the
result of Amdahl's law, as you point out. (upon re-reading your message,
I see that perhaps what you meant by "noise" is exactly this.)
E.
next prev parent reply other threads:[~2017-03-11 2:25 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-10 1:23 [Qemu-devel] Benchmarking linux-user performance Emilio G. Cota
2017-03-10 11:45 ` Dr. David Alan Gilbert
2017-03-10 11:48 ` Peter Maydell
2017-03-11 2:25 ` Emilio G. Cota [this message]
2017-03-11 15:02 ` Peter Maydell
2017-03-11 2:18 ` Emilio G. Cota
2017-03-14 17:06 ` Dr. David Alan Gilbert
2017-03-16 17:13 ` Emilio G. Cota
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