On Fri, Nov 14, 2008 at 16:38, Michael Kerrisk <mtk.manpages@xxxxxxxxxxxxxx> wrote: > [CC += "Paul Jackson" <pj@xxxxxxx>, who might want to Ack the patch below] > >>> This might be obvious to all of you, but it wasn't to me... The CPU set used >>> for the affinity is the intersection of the set passed to >>> pthread_setaffinity_np() and the set of processors supported by the >>> kernel... >>> >>> That's why your example shall work, even if the system where it runs has >>> less than 8 processors. >> >> It's true. The page should say something to make this clearer. I >> added this text to NOTES >> >> After a call to pthread_setaffinity_np(3), the set of >> CPUs on which the thread will actually run is the inter- >> section of the set specified in the cpuset argument and >> the set of CPUs actually present on the system. The sys- >> tem may further restrict the set of CPUs on which the >> thread runs if the "cpuset" mechanism described in >> cpuset(7) is being used. These restrictions on the >> actual set of CPUs on which the thread will run are >> silently imposed by the kernel. > > Of course, the sched_setaffinity.2 page also deserves similar text. I > made the change below. > > Look ok? Yes. Thanks. Bert > > Cheers, > > Michael > > --- a/man2/sched_setaffinity.2 > +++ b/man2/sched_setaffinity.2 > > @@ -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 > -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
