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libgomp.texi (GOMP_CPU_AFFINITY): Updated.

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2007-04-19  Daniel Franke  <franke.daniel@gmail.com>

        * libgomp.texi (GOMP_CPU_AFFINITY): Updated.

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Daniel Franke 2007-04-19 15:36:34 -04:00 committed by Daniel Franke
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@ -1,3 +1,7 @@
2007-04-19 Daniel Franke <franke.daniel@gmail.com>
* libgomp.texi (GOMP_CPU_AFFINITY): Updated.
2007-04-16 Matthias Klose <doko@debian.org>
* configure.tgt (i[456]86-*-linux*): Only add ia32 specific

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libgomp/libgomp.texi
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@ -895,14 +895,25 @@ dynamic scheduling and a chunk size of 1 is used.
@cindex Environment Variable
@table @asis
@item @emph{Description}:
A patch for this extension has been submitted, but was not yet applied at the
time of writing.
Binds threads to specific CPUs. The variable should contain a space- or
comma-separated list of CPUs. This list may contain different kind of
entries: either single CPU numbers in any order, a range of CPUs (M-N)
or a range with some stride (M-N:S). CPU numbers are zero based. For example,
@code{GOMP_CPU_AFFINITY="0 3 1-2 4-15:2"} will bind the initial thread
to CPU 0, the second to CPU 3, the third to CPU 1, the fourth to
CPU 2, the fifth to CPU 4, the sixth through tenth to CPUs 6, 8, 10, 12,
and 14 respectively and then start assigning back from the beginning of
the list. @code{GOMP_CPU_AFFINITY=0} binds all threads to CPU 0.
@item @emph{Reference}:
@uref{http://gcc.gnu.org/ml/gcc-patches/2006-05/msg00982.html,
GCC Patches Mailinglist}
@uref{http://gcc.gnu.org/ml/gcc-patches/2006-05/msg01133.html,
GCC Patches Mailinglist}
There is no GNU OpenMP library routine to determine whether a CPU affinity
specification is in effect. As a workaround, language-specific library
functions, e.g., @code{getenv} in C or @code{GET_ENVIRONMENT_VARIABLE} in
Fortran, may be used to query the setting of the @code{GOMP_CPU_AFFINITY}
environment variable. A defined CPU affinity on startup cannot be changed
or disabled during the runtime of the application.
If this environment variable is omitted, the host system will handle the
assignment of threads to CPUs.
@end table