Re: Proposal: Build timers

[zimoun <zimon.toutoune@gmail.com>]

Hi,

On Tue, 23 Nov 2021 at 07:05, Julien Lepiller <julien@lepiller.eu> wrote:

> LFS has a notion of a Standard Build Unit (SBU), that is the build
> time of a particular package on your machine. Each package build time
> is estimated in SBU. However, they do not take threads into account,
> because the relation is not exactly proportional (some parts are
> linear, there is some overhead, …). SBUs change quite often with
> versions, so I don't think averaging on different versions/derivations
> would make a lot of sense… But I suppose this info could help
> determine how long it should take to build the same derivation or a
> similar one.

Thanks for the SBU pointer.  This webpage [1] provides some details.
But I do not find the mentioned table.  I would see more numbers about
averages and standard derivation.

Moreover, I am confused, here [2] GCC@11.2.00 requires 26+56 SBU.  And
there [3] it says 164 SBU.  Why is it so different?


I am not convinced such SBUs makes sense for x86_64 because for instance
my laptop (4 cores+SSD) is different from my desktop (4 cores+HDD) and
really different from my workstation (64 cores+mix).  From my
understanding, this SBU makes sense in the LFS context because machines
are, from my opinion, not so much heterogeneous.

However, other architectures are generally more homogeneous machines.
And because substitutes are less available, maybe such unit could be
worth as a rough indicator.


1: <https://www.linuxfromscratch.org/~bdubbs/about.html>
2: <https://www.linuxfromscratch.org/blfs/view/svn/general/gcc.html>
3: <https://www.linuxfromscratch.org/lfs/view/stable/chapter08/gcc.html>

Cheers,
simon