209 lines
7.7 KiB
Diff
209 lines
7.7 KiB
Diff
|
commit cda99af14e82b4bb6abaecd717ebe3b57c0aa534
|
||
|
|
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
|
||
|
|
Date: Mon Sep 6 12:28:24 2021 -0300
|
||
|
|
|
||
|
|
linux: Simplify get_nprocs
|
||
|
|
|
||
|
|
This patch simplifies the memory allocation code and uses the sched
|
||
|
|
routines instead of reimplement it. This still uses a stack
|
||
|
|
allocation buffer, so it can be used on malloc initialization code.
|
||
|
|
|
||
|
|
Linux currently supports at maximum of 4096 cpus for most architectures:
|
||
|
|
|
||
|
|
$ find -iname Kconfig | xargs git grep -A10 -w NR_CPUS | grep -w range
|
||
|
|
arch/alpha/Kconfig- range 2 32
|
||
|
|
arch/arc/Kconfig- range 2 4096
|
||
|
|
arch/arm/Kconfig- range 2 16 if DEBUG_KMAP_LOCAL
|
||
|
|
arch/arm/Kconfig- range 2 32 if !DEBUG_KMAP_LOCAL
|
||
|
|
arch/arm64/Kconfig- range 2 4096
|
||
|
|
arch/csky/Kconfig- range 2 32
|
||
|
|
arch/hexagon/Kconfig- range 2 6 if SMP
|
||
|
|
arch/ia64/Kconfig- range 2 4096
|
||
|
|
arch/mips/Kconfig- range 2 256
|
||
|
|
arch/openrisc/Kconfig- range 2 32
|
||
|
|
arch/parisc/Kconfig- range 2 32
|
||
|
|
arch/riscv/Kconfig- range 2 32
|
||
|
|
arch/s390/Kconfig- range 2 512
|
||
|
|
arch/sh/Kconfig- range 2 32
|
||
|
|
arch/sparc/Kconfig- range 2 32 if SPARC32
|
||
|
|
arch/sparc/Kconfig- range 2 4096 if SPARC64
|
||
|
|
arch/um/Kconfig- range 1 1
|
||
|
|
arch/x86/Kconfig-# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
|
||
|
|
arch/x86/Kconfig- range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
|
||
|
|
arch/xtensa/Kconfig- range 2 32
|
||
|
|
|
||
|
|
With x86 supporting 8192:
|
||
|
|
|
||
|
|
arch/x86/Kconfig
|
||
|
|
976 config NR_CPUS_RANGE_END
|
||
|
|
977 int
|
||
|
|
978 depends on X86_64
|
||
|
|
979 default 8192 if SMP && CPUMASK_OFFSTACK
|
||
|
|
980 default 512 if SMP && !CPUMASK_OFFSTACK
|
||
|
|
981 default 1 if !SMP
|
||
|
|
|
||
|
|
So using a maximum of 32k cpu should cover all cases (and I would
|
||
|
|
expect once we start to have many more CPUs that Linux would provide
|
||
|
|
a more straightforward way to query for such information).
|
||
|
|
|
||
|
|
A test is added to check if sched_getaffinity can successfully return
|
||
|
|
with large buffers.
|
||
|
|
|
||
|
|
Checked on x86_64-linux-gnu and i686-linux-gnu.
|
||
|
|
|
||
|
|
Reviewed-by: Florian Weimer <fweimer@redhat.com>
|
||
|
|
(cherry picked from commit 33099d72e41cf8a129b362e9709eb2be9372d844)
|
||
|
|
|
||
|
|
diff --git a/posix/Makefile b/posix/Makefile
|
||
|
|
index a5229777eeb0e067..61fcdf015b4ec83b 100644
|
||
|
|
--- a/posix/Makefile
|
||
|
|
+++ b/posix/Makefile
|
||
|
|
@@ -107,7 +107,8 @@ tests := test-errno tstgetopt testfnm runtests runptests \
|
||
|
|
tst-sysconf-empty-chroot tst-glob_symlinks tst-fexecve \
|
||
|
|
tst-glob-tilde test-ssize-max tst-spawn4 bug-regex37 \
|
||
|
|
bug-regex38 tst-regcomp-truncated tst-spawn-chdir \
|
||
|
|
- tst-wordexp-nocmd tst-execveat tst-spawn5
|
||
|
|
+ tst-wordexp-nocmd tst-execveat tst-spawn5 \
|
||
|
|
+ tst-sched_getaffinity
|
||
|
|
|
||
|
|
# Test for the glob symbol version that was replaced in glibc 2.27.
|
||
|
|
ifeq ($(have-GLIBC_2.26)$(build-shared),yesyes)
|
||
|
|
diff --git a/posix/tst-sched_getaffinity.c b/posix/tst-sched_getaffinity.c
|
||
|
|
new file mode 100644
|
||
|
|
index 0000000000000000..db9d517a96fdd99e
|
||
|
|
--- /dev/null
|
||
|
|
+++ b/posix/tst-sched_getaffinity.c
|
||
|
|
@@ -0,0 +1,48 @@
|
||
|
|
+/* Tests for sched_getaffinity with large buffers.
|
||
|
|
+ Copyright (C) 2021 Free Software Foundation, Inc.
|
||
|
|
+ This file is part of the GNU C Library.
|
||
|
|
+
|
||
|
|
+ The GNU C Library is free software; you can redistribute it and/or
|
||
|
|
+ modify it under the terms of the GNU Lesser General Public
|
||
|
|
+ License as published by the Free Software Foundation; either
|
||
|
|
+ version 2.1 of the License, or (at your option) any later version.
|
||
|
|
+
|
||
|
|
+ The GNU C Library is distributed in the hope that it will be useful,
|
||
|
|
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||
|
|
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
||
|
|
+ Lesser General Public License for more details.
|
||
|
|
+
|
||
|
|
+ You should have received a copy of the GNU Lesser General Public
|
||
|
|
+ License along with the GNU C Library; if not, see
|
||
|
|
+ <https://www.gnu.org/licenses/>. */
|
||
|
|
+
|
||
|
|
+#include <array_length.h>
|
||
|
|
+#include <sched.h>
|
||
|
|
+#include <support/check.h>
|
||
|
|
+
|
||
|
|
+/* NB: this test may fail on system with more than 32k cpus. */
|
||
|
|
+
|
||
|
|
+static int
|
||
|
|
+do_test (void)
|
||
|
|
+{
|
||
|
|
+ /* The values are larger than the default cpu_set_t. */
|
||
|
|
+ const int bufsize[] = { 1<<11, 1<<12, 1<<13, 1<<14, 1<<15, 1<<16, 1<<17 };
|
||
|
|
+ int cpucount[array_length (bufsize)];
|
||
|
|
+
|
||
|
|
+ for (int i = 0; i < array_length (bufsize); i++)
|
||
|
|
+ {
|
||
|
|
+ cpu_set_t *cpuset = CPU_ALLOC (bufsize[i]);
|
||
|
|
+ TEST_VERIFY (cpuset != NULL);
|
||
|
|
+ size_t size = CPU_ALLOC_SIZE (bufsize[i]);
|
||
|
|
+ TEST_COMPARE (sched_getaffinity (0, size, cpuset), 0);
|
||
|
|
+ cpucount[i] = CPU_COUNT_S (size, cpuset);
|
||
|
|
+ CPU_FREE (cpuset);
|
||
|
|
+ }
|
||
|
|
+
|
||
|
|
+ for (int i = 0; i < array_length (cpucount) - 1; i++)
|
||
|
|
+ TEST_COMPARE (cpucount[i], cpucount[i + 1]);
|
||
|
|
+
|
||
|
|
+ return 0;
|
||
|
|
+}
|
||
|
|
+
|
||
|
|
+#include <support/test-driver.c>
|
||
|
|
diff --git a/sysdeps/unix/sysv/linux/getsysstats.c b/sysdeps/unix/sysv/linux/getsysstats.c
|
||
|
|
index 120ce1bb756b09cc..61d20e7bab8640f2 100644
|
||
|
|
--- a/sysdeps/unix/sysv/linux/getsysstats.c
|
||
|
|
+++ b/sysdeps/unix/sysv/linux/getsysstats.c
|
||
|
|
@@ -29,61 +29,29 @@
|
||
|
|
#include <sys/sysinfo.h>
|
||
|
|
#include <sysdep.h>
|
||
|
|
|
||
|
|
-/* Compute the population count of the entire array. */
|
||
|
|
-static int
|
||
|
|
-__get_nprocs_count (const unsigned long int *array, size_t length)
|
||
|
|
-{
|
||
|
|
- int count = 0;
|
||
|
|
- for (size_t i = 0; i < length; ++i)
|
||
|
|
- if (__builtin_add_overflow (count, __builtin_popcountl (array[i]),
|
||
|
|
- &count))
|
||
|
|
- return INT_MAX;
|
||
|
|
- return count;
|
||
|
|
-}
|
||
|
|
-
|
||
|
|
-/* __get_nprocs with a large buffer. */
|
||
|
|
-static int
|
||
|
|
-__get_nprocs_large (void)
|
||
|
|
-{
|
||
|
|
- /* This code cannot use scratch_buffer because it is used during
|
||
|
|
- malloc initialization. */
|
||
|
|
- size_t pagesize = GLRO (dl_pagesize);
|
||
|
|
- unsigned long int *page = __mmap (0, pagesize, PROT_READ | PROT_WRITE,
|
||
|
|
- MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
|
||
|
|
- if (page == MAP_FAILED)
|
||
|
|
- return 2;
|
||
|
|
- int r = INTERNAL_SYSCALL_CALL (sched_getaffinity, 0, pagesize, page);
|
||
|
|
- int count;
|
||
|
|
- if (r > 0)
|
||
|
|
- count = __get_nprocs_count (page, pagesize / sizeof (unsigned long int));
|
||
|
|
- else if (r == -EINVAL)
|
||
|
|
- /* One page is still not enough to store the bits. A more-or-less
|
||
|
|
- arbitrary value. This assumes t hat such large systems never
|
||
|
|
- happen in practice. */
|
||
|
|
- count = GLRO (dl_pagesize) * CHAR_BIT;
|
||
|
|
- else
|
||
|
|
- count = 2;
|
||
|
|
- __munmap (page, GLRO (dl_pagesize));
|
||
|
|
- return count;
|
||
|
|
-}
|
||
|
|
-
|
||
|
|
int
|
||
|
|
__get_nprocs (void)
|
||
|
|
{
|
||
|
|
- /* Fast path for most systems. The kernel expects a buffer size
|
||
|
|
- that is a multiple of 8. */
|
||
|
|
- unsigned long int small_buffer[1024 / CHAR_BIT / sizeof (unsigned long int)];
|
||
|
|
- int r = INTERNAL_SYSCALL_CALL (sched_getaffinity, 0,
|
||
|
|
- sizeof (small_buffer), small_buffer);
|
||
|
|
+ enum
|
||
|
|
+ {
|
||
|
|
+ max_num_cpus = 32768,
|
||
|
|
+ cpu_bits_size = CPU_ALLOC_SIZE (32768)
|
||
|
|
+ };
|
||
|
|
+
|
||
|
|
+ /* This cannot use malloc because it is used on malloc initialization. */
|
||
|
|
+ __cpu_mask cpu_bits[cpu_bits_size / sizeof (__cpu_mask)];
|
||
|
|
+ int r = INTERNAL_SYSCALL_CALL (sched_getaffinity, 0, cpu_bits_size,
|
||
|
|
+ cpu_bits);
|
||
|
|
if (r > 0)
|
||
|
|
- return __get_nprocs_count (small_buffer, r / sizeof (unsigned long int));
|
||
|
|
+ return CPU_COUNT_S (cpu_bits_size, (cpu_set_t*) cpu_bits);
|
||
|
|
else if (r == -EINVAL)
|
||
|
|
- /* The kernel requests a larger buffer to store the data. */
|
||
|
|
- return __get_nprocs_large ();
|
||
|
|
- else
|
||
|
|
- /* Some other error. 2 is conservative (not a uniprocessor
|
||
|
|
- system, so atomics are needed). */
|
||
|
|
- return 2;
|
||
|
|
+ /* The input buffer is still not enough to store the number of cpus. This
|
||
|
|
+ is an arbitrary values assuming such systems should be rare and there
|
||
|
|
+ is no offline cpus. */
|
||
|
|
+ return max_num_cpus;
|
||
|
|
+ /* Some other error. 2 is conservative (not a uniprocessor system, so
|
||
|
|
+ atomics are needed). */
|
||
|
|
+ return 2;
|
||
|
|
}
|
||
|
|
libc_hidden_def (__get_nprocs)
|
||
|
|
weak_alias (__get_nprocs, get_nprocs)
|