| Description |
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libsysconfcpus is an $LD_PRELOAD library that intercepts calls to
sysconf(), and adjusts the responses for _SC_NPROCESSORS_CONF
and _SC_NPROCESSORS_ONLN, which are used to determine the number of
processors available (either configured or online) at runtime in a system.
Unfortunately, some closed- source software assumes that all of these
processors may be used for computation, which is an assumption that is
frequently not true on multiuser and HPC systems. Thus, libsysconfcpus
provides a simple, non-intrusive way of adjusting the behaviour of such
software (when it is dynamically linked).
In addition, libsysconfcpus is a small, simple example of how to use
$LD_PRELOAD to do function call interception on glibc and POSIX
systems. It is hoped that it is useful not only inherently, but also for
learning about $LD_PRELOAD, and as a template or skeleton
LD_PRELOAD library. Its from-scratch development was used to
illustrate LD_PRELOAD usage in the "Fun with LD_PRELOAD" presentation
by the author at linux.conf.au 2009 in Hobart.
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| Downloads |
- Latest version: 0.5
- ChangeLog
- Older versions:
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| Installation |
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Standard autoconf process: ./configure && make && make install
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| Usage |
sysconfcpus [options] <program> [args...]
Valid options are:
-v, --version Display the sysconfcpus version
-h, --help Display this help
-d, --debug Display debug info
-n, --num <n> Number of processors (both conf and onln)
-c, --conf <n> Number of processors (conf(igured))
-o, --onln <n> Number of processors (online)
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| Examples |
$ test-sysconfcpus
sysconf(_SC_NPROCESSORS_CONF) = 2
sysconf(_SC_NPROCESSORS_ONLN) = 2
$ sysconfcpus -n 8 test-sysconfcpus
sysconf(_SC_NPROCESSORS_CONF) = 8
sysconf(_SC_NPROCESSORS_ONLN) = 8
$ sysconfcpus -c 8 -o 6 test-sysconfcpus
sysconf(_SC_NPROCESSORS_CONF) = 8
sysconf(_SC_NPROCESSORS_ONLN) = 6
$
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