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///////////////////////////////////////////////////////////////////////////////
//
/// \file hardware.c
/// \brief Detection of available hardware resources
//
// Copyright (C) 2007 Lasse Collin
//
// This program 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.
//
// This program 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.
//
///////////////////////////////////////////////////////////////////////////////
#include "private.h"
#include "physmem.h"
/// Maximum number of free *coder* threads. This can be set with
/// the --threads=NUM command line option.
size_t opt_threads = 1;
/// Number of bytes of memory to use at maximum (only a rough limit).
/// This can be set with the --memory=NUM command line option.
/// If no better value can be determined, the default is 14 MiB, which
/// should be quite safe even for older systems while still allowing
/// reasonable compression ratio.
size_t opt_memory = 14 * 1024 * 1024;
/// Get the amount of physical memory, and set opt_memory to 1/3 of it.
/// User can then override this with --memory command line option.
static void
hardware_memory(void)
{
uint64_t mem = physmem();
if (mem != 0) {
mem /= 3;
#if UINT64_MAX > SIZE_MAX
if (mem > SIZE_MAX)
mem = SIZE_MAX;
#endif
opt_memory = mem;
}
return;
}
/// Get the number of CPU cores, and set opt_threads to default to that value.
/// User can then override this with --threads command line option.
static void
hardware_cores(void)
{
#if defined(HAVE_NUM_PROCESSORS_SYSCONF)
const long cpus = sysconf(_SC_NPROCESSORS_ONLN);
if (cpus > 0)
opt_threads = (size_t)(cpus);
#elif defined(HAVE_NUM_PROCESSORS_SYSCTL)
int name[2] = { CTL_HW, HW_NCPU };
int cpus;
size_t cpus_size = sizeof(cpus);
if (!sysctl(name, &cpus, &cpus_size, NULL, NULL)
&& cpus_size == sizeof(cpus) && cpus > 0)
opt_threads = (size_t)(cpus);
#endif
// Limit opt_threads so that maximum number of threads doesn't exceed.
#if defined(_SC_THREAD_THREADS_MAX)
const long threads_max = sysconf(_SC_THREAD_THREADS_MAX);
if (threads_max > 0 && (size_t)(threads_max) < opt_threads)
opt_threads = (size_t)(threads_max);
#elif defined(PTHREAD_THREADS_MAX)
if (opt_threads > PTHREAD_THREADS_MAX)
opt_threads = PTHREAD_THREADS_MAX;
#endif
return;
}
extern void
hardware_init(void)
{
hardware_memory();
hardware_cores();
return;
}
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