Re: Interesting scheduling times

Linus Torvalds (torvalds@transmeta.com)
Fri, 18 Sep 1998 23:05:16 -0700 (PDT)


On Fri, 18 Sep 1998, Linus Torvalds wrote:
>
> Ok, let's do something that all parties can live with:
> - the the AT_FPUCW entry doesn't exist, Ulrich defaults to the state that
> has been cleared with "fninit" (apply applicable "normal default value"
> for all architectures)
> - if the AT_FPUCW entry exists, Ulrich can use that instead.
>
> Ulrich has to do something like the above anyway, as no current kernel
> will have the AT_FPUCW entry.

In fact, thinking some more about it, it strikes me that the proper
approach is to just do:
- the shared library just assumes that the startup state is always the
state that has been introduced by a "fninit" (that's what Linux has
done since version 0.11, modulo bugs)
- if that ever changes, _than_ can we start thinking about it.

Let's face it: the whole _idea_ with shared libraries is that you share
code AND that you're able to react to changes in the OS without having to
recompile all your binaries.

As such, a shared library that imposes changes on the OS is just a stupid
idea. You shouldn't go searching for problems you think might be an issue
some day, you should fix problems you know about. FPUCW is not a problem
today, and as far as I can tell there is no reason why it should ever
become one.

Let's aim for a fast, lean and mean shared library rather than bloating it
up without good reason. I already hate how all my binaries do this
completely stupid search for some random "locale" file even though I don't
have one and never asked for one, and it just slows the system down simply
because of a stupid shared library.

Linus

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