Gentoo Linux vs. Linaro ARM Benchmarks

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Originally Posted by Rashyskel

As an owner of an ODROID-X with a little free time, I'd love to checkout Gentoo.
But I did not see a link to a disk image anywhere!

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Well, the whole idea of Gentoo is that there are no disk images. You compile everything from scratch. It takes ages, but in the end all the code is hyper-optimised for your hardware, which is fairly important for slow devices. If you're asking about the images used in benchmarking in order to reproduce the results, though, then it's another matter.

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Originally Posted by RealNC

The article claims that Gentoo Stable is using GCC 4.7. This is not the case. Stable ("arch") is using GCC 4.5.4, while Testing ("~arch") is using 4.6.3. GCC 4.7 is actually hard-masked and marked as experimental. You cannot install it, unless you unmask it (in Gentoo, that means telling the system "I'm about to potentially shoot myself in the foot, and yes, that's what I want.")

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Yea, I noticed that as well. Also, I installed 4.7 on my device manually, but even then it installs into a new slot, and by default the old compiler is used.

It is quite unreasonable to expect a custom compiled distribution to be slower than a generic compiled distribution (unless the system-admin was braindamaged) so no surprises here.

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Originally Posted by RealNC

Stable ("arch") is using GCC 4.5.4, while Testing ("~arch") is using 4.6.3

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lol and I was already wondering if I had missed something when I read that. But then I thought, okay, maybe it's time for a --sync on the box. :)

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Originally Posted by GreatEmerald

Yea, I noticed that as well. Also, I installed 4.7 on my device manually, but even then it installs into a new slot, and by default the old compiler is used.

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This doesn't seem to be the case with this particular image. The article specifically mentions that GCC 4.7 was used.

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Originally Posted by Ragas

It is quite unreasonable to expect a custom compiled distribution to be slower than a generic compiled distribution

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From looking at compiler details on page 1, the Linaro install was no less specific to the hardware than Gentoo was.

I think the difference is almost entirely due to GCC version and CPU governor.

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Originally Posted by GreatEmerald

Also, I installed 4.7 on my device manually, but even then it installs into a new slot, and by default the old compiler is used.

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One can easily run gcc-config to switch between multiple installed gcc versions in gentoo. But you probably already know this :) Another interesting trick is to tune gcc configuration, which can be done in the following way:

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mkdir /etc/portage/env
mkdir /etc/portage/env/sys-devel
echo 'EXTRA_ECONF="--with-cpu=cortex-a9 --with-fpu=neon"' > /etc/portage/env/sys-devel/gcc
emerge sys-devel/gcc

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The optimization flags are normally specified in CFLAGS variable from /etc/make.conf, but changing gcc configuration is more reliable because it has global effect (even for the packages not built by portage). In particular, this is a good way to deliver CPU specific optimization settings to phoronix-test-suite. Also you can add "--with-mode=thumb" option for a fair comparison with ubuntu/linaro.

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Originally Posted by RealNC

The article claims that Gentoo Stable is using GCC 4.7. This is not the case. Stable ("arch") is using GCC 4.5.4, while Testing ("~arch") is using 4.6.3. GCC 4.7 is actually hard-masked and marked as experimental. You cannot install it, unless you unmask it (in Gentoo, that means telling the system "I'm about to potentially shoot myself in the foot, and yes, that's what I want.")

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The articles claims that Gentoo stable was compiled with GCC 4.7, which you can do, although as you say, it is unsupported.

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Originally Posted by RealNC

So I'd say this benchmark is bogus. If you installed GCC 4.7 on Gentoo, you should have done the same for Linaro. Since you didn't do that, the benchmark is highly biased.

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How do you propose that be done for Linaro? As far as I know. Linaro distributes binaries while Gentoo distributes source code. Installing a different system compiler on Linaro will not make the binaries that they distribute faster.

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Edit:
Also, if GCC was upgraded to a non-stable (and even non-testing) package version, then who knows what else was. I suspect the person who made the images for Phoronix didn't even mention this.

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Gentoo developers do this all the time, mainly because we are the people who fix the bugs when things go wrong. If this were a Gentoo developer's system, it would not be surprising for it to use the latest GCC.

With that said, I would love to know who this Robert Sanders is. We don't have any active or retired developers by the name of Robert Sanders:

http://www.gentoo.org/proj/en/devrel...l/userinfo.xml
http://www.gentoo.org/proj/en/devrel...Filter=Retired

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Originally Posted by ryao

The articles claims that Gentoo stable was compiled with GCC 4.7, which you can do, although as you say, it is unsupported.

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If you have GCC 4.7, it's not Gentoo Stable anymore.

I don't disagree* with anything else you said, since it's not the point. The point is that Gentoo Stable was not tested in this benchmark.

* Well, maybe with not installing GCC 4.7 in Linaro. The Phronix Test Suite is built from source, so why wouldn't GCC 4.7 affect the results? I say it would affect them greatly.

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Originally Posted by RealNC

If you have GCC 4.7, it's not Gentoo Stable anymore.

I don't disagree* with anything else you said, since it's not the point. The point is that Gentoo Stable was not tested in this benchmark.

* Well, maybe with not installing GCC 4.7 in Linaro. The Phronix Test Suite is built from source, so why wouldn't GCC 4.7 affect the results? I say it would affect them greatly.

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I assumed that the phoronix test suite was a bunch of scripts that used the system libraries and binaries. Is that incorrect?

By the way, I really would like to know who this Robert Sanders is. Michael claims that he was given shell access to a "board to be used as the primary build host for Gentoo weekly ARM stages". This makes no sense to me because I was under the impression that the release engineering team cross compiled the stages using catalyst.

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Originally Posted by ryao

With that said, I would love to know who this Robert Sanders is. We don't have any active or retired developers by the name of Robert Sanders: http://www.gentoo.org/proj/en/devrel...l/userinfo.xml

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The people on #gentoo-embedded irc channel say that he is 'dagger'.