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- fix sched_setaffinity(2) page - add an EXAMPLE and new NOTES

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Ivana Varekova 2009-12-02 14:42:05 +00:00
parent 7a34b70dd8
commit afa5b3666b
2 changed files with 70 additions and 1 deletions
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64
man-pages-3.22-sched_setaffinity.patch Normal file
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@ -0,0 +1,64 @@
diff -up man-pages-3.22/man2/sched_setaffinity.2.orig man-pages-3.22/man2/sched_setaffinity.2
--- man-pages-3.22/man2/sched_setaffinity.2.orig 2009-07-25 08:53:26.000000000 +0200
+++ man-pages-3.22/man2/sched_setaffinity.2 2009-12-02 15:29:17.000000000 +0100
@@ -212,6 +212,60 @@ system call returns the size (in bytes)
.I cpumask_t
data type that is used internally by the kernel to
represent the CPU set bit mask.
+
+The \fBcpu_set_t\fR affinity mask size provided by glibc only allows for upto
+1024 CPUs. It is possible to build Linux kernels with greater than 1024
+CPUs. Any application using the statically sized \fBcpu_set_t\fR will fail
+with \fBEINVAL\fR on such kernels. It is thus recommended that applications
+avoid using the statically sized \fBcpu_set_t\fR type, and instead dynamically
+allocate a mask using the CPU_*_S macros described in the \fBCPU_SET(3)\fR man
+page. Since it is not possible to determine ahead of time what \fBNR_CPUS\fR
+value the kernel was built with, applications must be prepared to catch
+\fBEINVAL\fR, and retry the command with a larger dynamically allocated mask.
+The example that follows illustrates portable usage.
+
+.SH EXAMPLE
+.nf
+ #define _GNU_SOURCE
+
+ #include <sched.h>
+ #include <stdio.h>
+ #include <errno.h>
+
+ int main(void)
+ {
+ cpu_set_t *mask;
+ size_t size;
+ int i;
+ int nrcpus = 1024;
+
+realloc:
+ mask = CPU_ALLOC(nrcpus);
+ size = CPU_ALLOC_SIZE(nrcpus);
+ CPU_ZERO_S(size, mask);
+ if ( sched_getaffinity(0, size, mask) == -1 ) {
+ CPU_FREE(mask);
+ if (errno == EINVAL &&
+ nrcpus < (1024 << 8)) {
+ nrcpus = nrcpus << 2;
+ goto realloc;
+ }
+ perror("sched_getaffinity");
+ return -1;
+ }
+
+ for ( i = 0; i < nrcpus; i++ ) {
+ if ( CPU_ISSET_S(i, size, mask) ) {
+ printf("CPU %d is set\n", (i+1));
+ }
+ }
+
+ CPU_FREE(mask);
+
+ return 0;
+ }
+.fi
+
.SH "SEE ALSO"
.BR clone (2),
.BR getcpu (2),

7
man-pages.spec
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@ -4,7 +4,7 @@
Summary: Man (manual) pages from the Linux Documentation Project
Name: man-pages
Version: 3.23
Release: 2%{?dist}
Release: 3%{?dist}
License: GPLv2+ and GPL+ and BSD and MIT and Copyright only and IEEE
Group: Documentation
URL: http://www.kernel.org/pub/linux/docs/manpages/
@ -33,6 +33,7 @@ Patch56: man-pages-3.22-strcpy.patch
Patch57: man-pages-3.22-nsswitch.conf.patch
Patch58: man-pages-3.23-proc.patch
Patch59: man-pages-3.23-ld.so.patch
Patch60: man-pages-3.22-sched_setaffinity.patch
Buildroot: %{_tmppath}/%{name}-%{version}-%{release}-root-%(%{__id_u} -n)
Autoreq: false
@ -64,6 +65,7 @@ rmdir man-pages-posix-%{posix_version}-%{posix_release}
%patch57 -p1
%patch58 -p1
%patch59 -p1
%patch60 -p1
### And now remove those we are not going to use:
@ -134,6 +136,9 @@ rm -rf $RPM_BUILD_ROOT
%lang(en) %{_mandir}/en/man*
%changelog
* Wed Dec 2 2009 Ivana Hutarova Varekova <varekova@redhat.com> - 3.22-7
- fix sched_setaffinity(2) page - add an EXAMPLE and new NOTES
* Wed Nov 18 2009 Ivana Varekova <varekova@redhat.com> - 3.23-2
- fix ld.so man-page (#532629)