glibc/posix/tst-sched_getaffinity.c
Adhemerval Zanella 33099d72e4 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>
2021-09-27 09:18:12 -03:00

49 lines
1.6 KiB
C

/* 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>