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///////////////////////////////////////////////////////////////////////////////
//
/// \file hardware.c
/// \brief Detection of available hardware resources
//
// Author: Lasse Collin
//
// This file has been put into the public domain.
// You can do whatever you want with this file.
//
///////////////////////////////////////////////////////////////////////////////
#include "private.h"
/// Maximum number of worker threads. This can be set with
/// the --threads=NUM command line option.
static uint32_t threads_max = 1;
/// Memory usage limit for compression
static uint64_t memlimit_compress;
/// Memory usage limit for decompression
static uint64_t memlimit_decompress;
/// Total amount of physical RAM
static uint64_t total_ram;
extern void
hardware_threads_set(uint32_t n)
{
if (n == 0) {
// Automatic number of threads was requested.
// If threading support was enabled at build time,
// use the number of available CPU cores. Otherwise
// use one thread since disabling threading support
// omits lzma_cputhreads() from liblzma.
#ifdef MYTHREAD_ENABLED
threads_max = lzma_cputhreads();
if (threads_max == 0)
threads_max = 1;
#else
threads_max = 1;
#endif
} else {
threads_max = n;
}
return;
}
extern uint32_t
hardware_threads_get(void)
{
return threads_max;
}
extern void
hardware_memlimit_set(uint64_t new_memlimit,
bool set_compress, bool set_decompress, bool is_percentage)
{
if (is_percentage) {
assert(new_memlimit > 0);
assert(new_memlimit <= 100);
new_memlimit = (uint32_t)new_memlimit * total_ram / 100;
}
if (set_compress) {
memlimit_compress = new_memlimit;
#if SIZE_MAX == UINT32_MAX
// FIXME?
//
// When running a 32-bit xz on a system with a lot of RAM and
// using a percentage-based memory limit, the result can be
// bigger than the 32-bit address space. Limiting the limit
// below SIZE_MAX for compression (not decompression) makes
// xz lower the compression settings (or number of threads)
// to a level that *might* work. In practice it has worked
// when using a 64-bit kernel that gives full 4 GiB address
// space to 32-bit programs. In other situations this might
// still be too high, like 32-bit kernels that may give much
// less than 4 GiB to a single application.
//
// So this is an ugly hack but I will keep it here while
// it does more good than bad.
//
// Use a value less than SIZE_MAX so that there's some room
// for the xz program and so on. Don't use 4000 MiB because
// it could look like someone mixed up base-2 and base-10.
const uint64_t limit_max = UINT64_C(4020) << 20;
// UINT64_MAX is a special case for the string "max" so
// that has to be handled specially.
if (memlimit_compress != UINT64_MAX
&& memlimit_compress > limit_max)
memlimit_compress = limit_max;
#endif
}
if (set_decompress)
memlimit_decompress = new_memlimit;
return;
}
extern uint64_t
hardware_memlimit_get(enum operation_mode mode)
{
// Zero is a special value that indicates the default. Currently
// the default simply disables the limit. Once there is threading
// support, this might be a little more complex, because there will
// probably be a special case where a user asks for "optimal" number
// of threads instead of a specific number (this might even become
// the default mode). Each thread may use a significant amount of
// memory. When there are no memory usage limits set, we need some
// default soft limit for calculating the "optimal" number of
// threads.
const uint64_t memlimit = mode == MODE_COMPRESS
? memlimit_compress : memlimit_decompress;
return memlimit != 0 ? memlimit : UINT64_MAX;
}
/// Helper for hardware_memlimit_show() to print one human-readable info line.
static void
memlimit_show(const char *str, uint64_t value)
{
// The memory usage limit is considered to be disabled if value
// is 0 or UINT64_MAX. This might get a bit more complex once there
// is threading support. See the comment in hardware_memlimit_get().
if (value == 0 || value == UINT64_MAX)
printf("%s %s\n", str, _("Disabled"));
else
printf("%s %s MiB (%s B)\n", str,
uint64_to_str(round_up_to_mib(value), 0),
uint64_to_str(value, 1));
return;
}
extern void
hardware_memlimit_show(void)
{
if (opt_robot) {
printf("%" PRIu64 "\t%" PRIu64 "\t%" PRIu64 "\n", total_ram,
memlimit_compress, memlimit_decompress);
} else {
// TRANSLATORS: Test with "xz --info-memory" to see if
// the alignment looks nice.
memlimit_show(_("Total amount of physical memory (RAM): "),
total_ram);
memlimit_show(_("Memory usage limit for compression: "),
memlimit_compress);
memlimit_show(_("Memory usage limit for decompression: "),
memlimit_decompress);
}
tuklib_exit(E_SUCCESS, E_ERROR, message_verbosity_get() != V_SILENT);
}
extern void
hardware_init(void)
{
// Get the amount of RAM. If we cannot determine it,
// use the assumption defined by the configure script.
total_ram = lzma_physmem();
if (total_ram == 0)
total_ram = (uint64_t)(ASSUME_RAM) * 1024 * 1024;
// Set the defaults.
hardware_memlimit_set(0, true, true, false);
return;
}
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