LDP
/
man-pages
mirror of https://github.com/mkerrisk/man-pages
0
1
Fork 0
Code Releases Activity

sched_setaffinity.2: Add note on system-imposed restrictions on CPUs actually used 

After Loic Domaigne's suggestion for pthread_setaffinity_np(3), add
similar text to this page noting that the system silently
limits the set of CPUs on which the process actually runs to
the set of CPUs physically present and the limits imposed by
cpuset(7).

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Reported-by: Loic Domaigne <tech@domaigne.com>
Acked-by: Bert Wesarg <bert.wesarg@googlemail.com>
This commit is contained in:
Michael Kerrisk 2008-11-14 10:35:45 -05:00
parent 553e8b962e
commit 9c7cf1820f
1 changed files with 18 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
man2/sched_setaffinity.2
View File

@ -32,7 +32,7 @@
.\" 2008-11-12, mtk, removed CPU_*() macro descriptions to a
.\" separate CPU_SET(3) page.
.\"
.TH SCHED_SETAFFINITY 2 2008-11-13 "Linux" "Linux Programmer's Manual"
.TH SCHED_SETAFFINITY 2 2008-11-14 "Linux" "Linux Programmer's Manual"
.SH NAME
sched_setaffinity, sched_getaffinity \- \
set and get a process's CPU affinity mask
@ -122,7 +122,10 @@ A supplied memory address was invalid.
.B EINVAL
The affinity bit mask
.I mask
contains no processors that are physically on the system.
contains no processors that are currently physically on the system
and permitted to the process according to any restrictions that
may be imposed by the "cpuset" mechanism described in
.BR cpuset (7).
.TP
.B EINVAL
.RB ( sched_getaffinity ()
@ -157,6 +160,19 @@ argument was removed, but was then restored in glibc 2.3.4, with type
.SH "CONFORMING TO"
These system calls are Linux-specific.
.SH "NOTES"
After a call to
.BR sched_setaffinity (),
the set of CPUs on which the process will actually run is
the intersection of the set specified in the
.I mask
argument and the set of CPUs actually present on the system.
The system may further restrict the set of CPUs on which the process
runs if the "cpuset" mechanism described in
.BR cpuset (7)
is being used.
These restrictions on the actual set of CPUs on which the process
will run are silently imposed by the kernel.
.BR sched_setscheduler (2)
has a description of the Linux scheduling scheme.
.PP