Re: [uml-devel] Re: Stop at startup on 2.6 NPTL hosts

[Blaisorblade <blaisorblade_spam@yahoo.it>]

On Wednesday 10 November 2004 09:36, stian@nixia.no wrote:
> > This fact (glibc caches getpid() results) was even known because already
> > posted, and I guessed that this could happen only with TLS support.
>
> That glibc caches getpid() has been a known issue before when people
> wanted to benchmark uml syscall speeds inside vs outside of UML using a
> simple libc-function.
In fact, it has been also said against SYSEMU benchmarks. Actually, it was 
obvious it didn't apply: in fact, this only happens with TLS, which is always 
disabled inside UML.

> A clone() call can't easily invalidate caches around 
> in libs that are stored in statics. But it should be mentioned on
> getpid()'s man/info page that the value might be cached.

> Perhaps sende the glibc dudes an email with the problem, and either get
> them to remove the cache or document it. Either way it will be a problem,
> since people might use a version of glibc then that caches getpid.. only
> work-around  is to use syscall() directly, or avoid using getpid() before
> clone().
The first one is better, I'm going to use it.

Bye
-- 
Paolo Giarrusso, aka Blaisorblade
Linux registered user n. 292729


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