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Re: [glibc] Fix Linux sysconf(_SC_NPROCESSORS_[CONF|ONLN]) performance problem
- From: Samuel Thibault <samuel dot thibault at ens-lyon dot org>
- To: Linus Torvalds <torvalds at linux-foundation dot org>
- Cc: Ulrich Drepper <drepper at gmail dot com>,Roland McGrath <roland at hack dot frob dot com>,"David S. Miller" <davem at davemloft dot net>,Andreas Schwab <schwab at redhat dot com>, libc-alpha at sourceware dot org
- Date: Thu, 16 Jun 2011 19:58:11 +0200
- Subject: Re: [glibc] Fix Linux sysconf(_SC_NPROCESSORS_[CONF|ONLN]) performance problem
- References: <BANLkTi=ousV=JtYzAYEnMVqqX6fnF_1z9Q@mail.gmail.com>
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