root/src/xz/hardware.c

DEFINITIONS

1. hardware_threadlimit_set
2. hardware_threadlimit_get
3. hardware_memlimit_set
4. hardware_memlimit_get
5. memlimit_show
6. hardware_memlimit_show
7. hardware_init

///////////////////////////////////////////////////////////////////////////////
//
/// \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"
#include "tuklib_cpucores.h"


/// Maximum number of free *coder* threads. This can be set with
/// the --threads=NUM command line option.
static uint32_t threadlimit;

/// 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_threadlimit_set(uint32_t new_threadlimit)
{
        if (new_threadlimit == 0) {
                // The default is the number of available CPU cores.
                threadlimit = tuklib_cpucores();
                if (threadlimit == 0)
                        threadlimit = 1;
        } else {
                threadlimit = new_threadlimit;
        }

        return;
}


extern uint32_t
hardware_threadlimit_get(void)
{
        return threadlimit;
}


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 (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);
        hardware_threadlimit_set(0);
        return;
}