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On some systems, the glibc can return 0 instead of cache-line size to
indicate the cache line sizes cannot be determined. This is comment
from glibc source code:
/* In general we cannot determine these values. Therefore we
return zero which indicates that no information is
available. */
As the goal of the check is to determine whether the L1 cache line size
is still 64 and we would use this value in case the sysconf() call is
not available, we can also ignore the invalid values returned by the
sysconf() call.
91 lines
2.1 KiB
C
91 lines
2.1 KiB
C
/*
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* Copyright (C) Internet Systems Consortium, Inc. ("ISC")
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*
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* SPDX-License-Identifier: MPL-2.0
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, you can obtain one at https://mozilla.org/MPL/2.0/.
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*
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* See the COPYRIGHT file distributed with this work for additional
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* information regarding copyright ownership.
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*/
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#include <inttypes.h>
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#include <isc/os.h>
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#include <isc/types.h>
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#include <isc/util.h>
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#include "os_p.h"
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static unsigned int isc__os_ncpus = 0;
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#ifdef HAVE_SYSCONF
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#include <unistd.h>
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static inline long
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sysconf_ncpus(void) {
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#if defined(_SC_NPROCESSORS_ONLN)
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return (sysconf((_SC_NPROCESSORS_ONLN)));
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#elif defined(_SC_NPROC_ONLN)
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return (sysconf((_SC_NPROC_ONLN)));
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#else /* if defined(_SC_NPROCESSORS_ONLN) */
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return (0);
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#endif /* if defined(_SC_NPROCESSORS_ONLN) */
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}
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#endif /* HAVE_SYSCONF */
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#if defined(HAVE_SYS_SYSCTL_H) && defined(HAVE_SYSCTLBYNAME)
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#include <sys/param.h> /* for NetBSD */
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#include <sys/sysctl.h>
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#include <sys/types.h> /* for FreeBSD */
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static int
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sysctl_ncpus(void) {
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int ncpu, result;
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size_t len;
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len = sizeof(ncpu);
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result = sysctlbyname("hw.ncpu", &ncpu, &len, 0, 0);
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if (result != -1) {
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return (ncpu);
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}
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return (0);
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}
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#endif /* if defined(HAVE_SYS_SYSCTL_H) && defined(HAVE_SYSCTLBYNAME) */
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static void
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ncpus_initialize(void) {
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#if defined(HAVE_SYSCONF)
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isc__os_ncpus = sysconf_ncpus();
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#endif /* if defined(HAVE_SYSCONF) */
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#if defined(HAVE_SYS_SYSCTL_H) && defined(HAVE_SYSCTLBYNAME)
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if (isc__os_ncpus <= 0) {
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isc__os_ncpus = sysctl_ncpus();
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}
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#endif /* if defined(HAVE_SYS_SYSCTL_H) && defined(HAVE_SYSCTLBYNAME) */
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if (isc__os_ncpus == 0) {
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isc__os_ncpus = 1;
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}
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}
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unsigned int
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isc_os_ncpus(void) {
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return (isc__os_ncpus);
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}
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void
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isc__os_initialize(void) {
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ncpus_initialize();
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#if defined(HAVE_SYSCONF) && defined(_SC_LEVEL1_DCACHE_LINESIZE)
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long s = sysconf(_SC_LEVEL1_DCACHE_LINESIZE);
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RUNTIME_CHECK((size_t)s == (size_t)ISC_OS_CACHELINE_SIZE || s <= 0);
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#endif
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}
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void
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isc__os_shutdown(void) {
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/* empty, but defined for completeness */;
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}
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