Re: [gentoo-user] Re: Gentoo speed comparison to other distros

[Mateusz Kowalczyk]

On 14/03/13 23:52, Dale wrote:
> Mateusz Kowalczyk wrote:
>> On 14/03/13 22:41, Dale wrote:
>>> Grant Edwards wrote:
>>>> On 2013-03-14, Dale <rdalek1967@×××××.com> wrote:
>>>>
>>>>> I was wondering.  Has anyone ever seen where a test as been done to
>>>>> compare the speed of Gentoo with other distros?  Maybe Gentoo compared
>>>>> to Redhat, Mandrake, Ubuntu and such?
>>>> I just did a test, and they're all the same.
>>>>
>>>> CDs/DVDS of various distros dropped from a height of 1m all hit the
>>>> floor simultaneously [there are random variations due to aerodynamic
>>>> instability of the disk shape, but it's the same for all distros]. If
>>>> launched horizontally with spin to provide attitude stability (thrown
>>>> like a frisbee), they all fly the same.
>>>>
>>>> The point being, you're going to have to define "speed".
>>>>
>>>> Does speed refer to
>>>>
>>>>  Installation time?
>>>>
>>>>  Boot time?
>>>>
>>>>  Linpack?
>>>>
>>>>  Dhrystone?
>>>>
>>>>  Whetstone?
>>>>
>>>>  Time for me to figure out how to fix a configuration problem?
>>>>
>>>>  Time to do to an update on a machine that's been unplugged for a year?
>>>>
>>>>  Time to to produce a packaged version of some random C program that
>>>>  comes with a Makefile that uses autotools?
>>>>
>>>>  Time for a reported bug to get fixed?
>>>>
>>>
>>> OK.  It appears not very many can figure out what I asked for.  So, let
>>> me spell it out for those who are challenged.  LOL   ;-)  Read some
>>> humor into that OK.
>>>
>>> Install a OS.  Run tests on a set of programs and record the time it
>>> takes to complete a certain task.  More tasks the better.
>>>
>>> Then install another OS on the same hardware.  Run tests on a set of
>>> programs and record the time it takes to complete a certain task.  More
>>> tasks the better.
>>>
>>> The object of this is, does Gentoo with the customization it allows run
>>> faster than some binary install that does NOT allow those controls?  In
>>> other words, can a Gentoo based install perform more efficiently than a
>>> binary based install like Redhat, Ubuntu or some other distro?
>>>
>>> I am NOT concerned about compile times or the install itself.
>>>
>>> Does that put the dots closer together for the challenged ones?  ROFL
>>>
>>> Dale
>>>
>>> :-)  :-)
>>>
>> The point of the challenged ones was that while we can take measurements
>> like these, it's rather meaningless to do so. The result will be
>> different for every single person out there depending on their
>> configuration, USE, CFLAGS and who knows what else.
>>
>> I can compile a package with support for 3 different DEs, few WMs, oss
>> and alsa and about a billion things I will never use. Does this make for
>> a more or less of a meaningful test than doing the same test with no
>> flags what so ever? There is no correct answer as it varies per user
>> basis. The most meaningful measurements that we can probably take would
>> be between different USE flags configurations. Maybe we can say that
>> package ‘foo’ with certain USE and CFLAGS runs in less average time than
>> the same package on a distro Bar.
>>
>> In my opinion, it would be far more meaningful to measure the effect of
>> different USE flags on the same package, *in relative time* on the same
>> system. This would give us more idea about the impact of each flag as
>> opposed to a very limited view of ‘package foo with certain specific USE
>> flags runs 10ms faster than the same package on the same hardware on a
>> binary distribution’. If you still want such measurements and you want
>> them to be somewhat meaningful to you, it is you who will have to take
>> them. Unless there are some gross inconsistencies in run times on
>> different distributions, we have no use for such measurement.
>>
>> Everyone understood what you asked for. It's _you_ that misunderstood
>> their explanation for why it's meaningless to ask such a question in the
>> first place.
>>
>
> I didn't miss anything.  I get what some are saying.  The reason for my
> question is this.  Gentoo allows a person to customize the OS to the
> specific hardware it is being run on.  Redhat and other binary distros
> don't allow this, unless you compile your own packages which is no
> longer really a binary install.
>
> So, if I install Redhat on my machine, would it be less efficient than
> my Gentoo install which is customized for my hardware?  Has someone else
> tested this and made it public?
>
> If people can't get this, never mind.
>
> Dale
>
> :-)  :-)
>

I don't think that it's plausible to take such measurement. We could set
every USE flag possible for the package we are benchmarking to try and
replicate the support for everything that the binary package is likely
to have. We also have to do this for all its dependencies (and their
dependencies and so on) to have nothing that could potentially influence
the measurement. Assuming that portage complies with this (it won't), we
compile the package with optimizations for our hardware. The result? We
probably have the same result on Gentoo and the other distro.

Why? The reason is simple: binary distributions provide packages
compiled with optimizations turned on for specific architectures. Unless
you are doing some unheard of optimizations for your obscure model of
the CPU, I don't imagine you'd get much advantage at all. If the
maintainer of the binary package compiles it with optimizations for an
i7 and you do the same, why should the performance be different?

If you install RedHat on your machine, it probably will be less
efficient than Gentoo but for a different reason. It won't be
(noticeably) more efficient because you've got your CFLAGS set in a
particular way but it because you only install the packages you actually
want and remove support for things you don't need. Why bloat a package
and waste cycles having it try to poll a service you might never
actually use? Gentoo lets you get rid (or never install in the first
place) of this kind of… bloat while you don't have much choice on a
binary package short of compiling everything by hand at which point you
should be using Gentoo to do it for you.

RedHat maintainers aren't stupid (you can probably tell I've never used
RH) – they will release packages optimized for architectures they will
run on. Overall you might get very slight performance boost because of
some CFLAG you enable but you might as well have worse performance
because you don't know as much about optimizations as the RH maintainers
and developers. Bah, you can even find examples on Gentoo wiki where
compiling certain packages with certain flags actually makes them slower
and not faster where usually the opposite is the case.

-- 
Mateusz K.