[glibc] Fix Linux sysconf(_SC_NPROCESSORS_[CONF|ONLN]) performance problem

[Samuel Thibault]

Linus Torvalds, le Thu 16 Jun 2011 09:38:55 -0700, a écrit :
>  - cache the value in a static variable, so that if/when there are
> multiple calls, we don't spend time recalculating the number of CPU's
> in the system unnecessarily.

Mmm, but what if the process starts with only one allowed CPU, and
then is given more CPUs? (either by making CPUs online, or by using
sched_setaffinity from an administration tool).

Samuel