This does not work with more than 1024 possible CPUs because sched_getaffinity is specified to return EINVAL in this case: cpu_set_t cs; if (sched_getaffinity (getpid (), sizeof (cs), &cs) != 0) { printf ("getaffinity failed: %m\n"); return 1; }
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The branch, master has been updated via 2359035ac52db69eb427c3b4b9d9297c98d2b225 (commit) from c100dca32a6859a47789ddcbb5679e74f8d92a41 (commit) Those revisions listed above that are new to this repository have not appeared on any other notification email; so we list those revisions in full, below. - Log ----------------------------------------------------------------- https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=2359035ac52db69eb427c3b4b9d9297c98d2b225 commit 2359035ac52db69eb427c3b4b9d9297c98d2b225 Author: Florian Weimer <fweimer@redhat.com> Date: Tue Nov 24 17:21:01 2015 +0100 Remove CPU set size checking from affinity functions [BZ #19143] With current kernel versions, the check does not reliably detect that unavailable CPUs are requested, for these reasons: (1) The kernel will silently ignore non-allowed CPUs, that is, CPUs which are physically present but disallowed for the thread based on system configuration. (2) Similarly, CPU bits which lack an online CPU (possible CPUs) are ignored. (3) The existing probing code assumes that the CPU mask size is a power of two and at least 1024. Neither has it to be a power of two, nor is the minimum possible value 1024, so the value determined is often too large. This means that the CPU set size check in glibc accepts CPU bits beyond the actual hard system limit. (4) Future kernel versions may not even have a fixed CPU set size. After the removal of the probing code, the kernel still returns EINVAL if no CPU in the requested set remains which can run the thread after the affinity change. Applications which care about the exact affinity mask will have to query it using sched_getaffinity after setting it. Due to the effects described above, this commit does not change this. The new tests supersede tst-getcpu, which is removed. This addresses bug 19164 because the new tests allocate CPU sets dynamically. * nptl/check-cpuset.h: Remove. * nptl/pthread_attr_setaffinity.c (__pthread_attr_setaffinity_new): Remove CPU set size check. * nptl/pthread_setattr_default_np.c (pthread_setattr_default_np): Likewise. * sysdeps/unix/sysv/linux/check-cpuset.h: Remove. * sysdeps/unix/sysv/linux/pthread_setaffinity.c (__kernel_cpumask_size, __determine_cpumask_size): Remove. (__pthread_setaffinity_new): Remove CPU set size check. * sysdeps/unix/sysv/linux/sched_setaffinity.c (__kernel_cpumask_size): Remove. (__sched_setaffinity_new): Remove CPU set size check. * manual/threads.texi (Default Thread Attributes): Remove stale reference to check_cpuset_attr, determine_cpumask_size in comment. * sysdeps/unix/sysv/linux/Makefile [$(subdir) == posix] (tests): Remove tst-getcpu. Add tst-affinity, tst-affinity-pid. [$(subdir) == nptl] (tests): Add tst-thread-affinity-pthread, tst-thread-affinity-pthread2, tst-thread-affinity-sched. * sysdeps/unix/sysv/linux/tst-affinity.c: New file. * sysdeps/unix/sysv/linux/tst-affinity-pid.c: New file. * sysdeps/unix/sysv/linux/tst-skeleton-affinity.c: New skeleton test file. * sysdeps/unix/sysv/linux/tst-thread-affinity-sched.c: New file. * sysdeps/unix/sysv/linux/tst-thread-affinity-pthread.c: New file. * sysdeps/unix/sysv/linux/tst-thread-affinity-pthread2.c: New file. * sysdeps/unix/sysv/linux/tst-thread-skeleton-affinity.c: New skeleton test file. * sysdeps/unix/sysv/linux/tst-getcpu.c: Remove. Superseded by tst-affinity-pid. ----------------------------------------------------------------------- Summary of changes: ChangeLog | 33 +++ NEWS | 8 + manual/threads.texi | 2 - nptl/check-cpuset.h | 32 --- nptl/pthread_attr_setaffinity.c | 6 - nptl/pthread_setattr_default_np.c | 5 - sysdeps/unix/sysv/linux/Makefile | 6 +- sysdeps/unix/sysv/linux/check-cpuset.h | 48 ---- sysdeps/unix/sysv/linux/pthread_setaffinity.c | 48 ---- sysdeps/unix/sysv/linux/sched_setaffinity.c | 37 --- sysdeps/unix/sysv/linux/tst-affinity-pid.c | 201 ++++++++++++++ sysdeps/unix/sysv/linux/tst-affinity.c | 43 +++ sysdeps/unix/sysv/linux/tst-getcpu.c | 59 ---- sysdeps/unix/sysv/linux/tst-skeleton-affinity.c | 278 +++++++++++++++++++ .../unix/sysv/linux/tst-skeleton-thread-affinity.c | 280 ++++++++++++++++++++ .../unix/sysv/linux/tst-thread-affinity-pthread.c | 49 ++++ .../unix/sysv/linux/tst-thread-affinity-pthread2.c | 95 +++++++ .../unix/sysv/linux/tst-thread-affinity-sched.c | 36 +++ 18 files changed, 1027 insertions(+), 239 deletions(-) delete mode 100644 nptl/check-cpuset.h delete mode 100644 sysdeps/unix/sysv/linux/check-cpuset.h create mode 100644 sysdeps/unix/sysv/linux/tst-affinity-pid.c create mode 100644 sysdeps/unix/sysv/linux/tst-affinity.c delete mode 100644 sysdeps/unix/sysv/linux/tst-getcpu.c create mode 100644 sysdeps/unix/sysv/linux/tst-skeleton-affinity.c create mode 100644 sysdeps/unix/sysv/linux/tst-skeleton-thread-affinity.c create mode 100644 sysdeps/unix/sysv/linux/tst-thread-affinity-pthread.c create mode 100644 sysdeps/unix/sysv/linux/tst-thread-affinity-pthread2.c create mode 100644 sysdeps/unix/sysv/linux/tst-thread-affinity-sched.c
Fixed in 2.23.