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| author | Florian Weimer <fweimer@redhat.com> | 2015-11-24 17:21:01 +0100 |
|---|---|---|
| committer | Florian Weimer <fweimer@redhat.com> | 2015-11-24 17:21:01 +0100 |
| commit | 2359035ac52db69eb427c3b4b9d9297c98d2b225 (patch) | |
| tree | 61cd8b4054f8f708b4d41b9427a989f547cf3a0c /manual/threads.texi | |
| parent | c100dca32a6859a47789ddcbb5679e74f8d92a41 (diff) | |
| download | glibc-2359035ac52db69eb427c3b4b9d9297c98d2b225.zip glibc-2359035ac52db69eb427c3b4b9d9297c98d2b225.tar.gz glibc-2359035ac52db69eb427c3b4b9d9297c98d2b225.tar.bz2 | |
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.
Diffstat (limited to 'manual/threads.texi')
| -rw-r--r-- | manual/threads.texi | 2 |
1 files changed, 0 insertions, 2 deletions
diff --git a/manual/threads.texi b/manual/threads.texi index 4d080d4..00cc725 100644 --- a/manual/threads.texi +++ b/manual/threads.texi @@ -111,8 +111,6 @@ failure. @c check_sched_priority_attr ok @c sched_get_priority_min dup ok @c sched_get_priority_max dup ok -@c check_cpuset_attr ok -@c determine_cpumask_size ok @c check_stacksize_attr ok @c lll_lock @asulock @aculock @c free dup @ascuheap @acsmem |