hardware.h File Reference

Detection of available hardware resources. More...

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Functions
void	hardware_init (void)
void	hardware_threads_set (uint32_t threadlimit)
uint32_t	hardware_threads_get (void)
	Get the maximum number of worker threads.
bool	hardware_threads_is_mt (void)
void	hardware_memlimit_set (uint64_t new_memlimit, bool set_compress, bool set_decompress, bool set_mtdec, bool is_percentage)
uint64_t	hardware_memlimit_get (enum operation_mode mode)
uint64_t	hardware_memlimit_mtenc_get (void)
bool	hardware_memlimit_mtenc_is_default (void)
uint64_t	hardware_memlimit_mtdec_get (void)
void	hardware_memlimit_show (void) lzma_attribute((__noreturn__))
	Display the amount of RAM and memory usage limits and exit.

Detailed Description

Detection of available hardware resources.

Function Documentation

hardware_init()

void hardware_init ( void )

extern

Initialize some hardware-specific variables, which are needed by other hardware_* functions.

hardware_memlimit_get()

uint64_t hardware_memlimit_get ( enum operation_mode mode )

extern

Get the current memory usage limit for compression or decompression. This is a hard limit that will not be exceeded. This is obeyed in both single-threaded and multithreaded modes.

hardware_memlimit_mtdec_get()

uint64_t hardware_memlimit_mtdec_get ( void )

extern

Get the current memory usage limit for multithreaded decompression. This is only used to reduce the number of threads. This limit can be exceeded if the number of threads are reduce to one. Then the value from hardware_memlimit_get() will be honored like in single-threaded mode.

hardware_memlimit_mtenc_get()

uint64_t hardware_memlimit_mtenc_get ( void )

extern

This returns a system-specific default value if all of the following conditions are true:

• An automatic number of threads was requested (–threads=0).
• –memlimit-compress wasn't used or it was reset to the default value by setting it to 0.

Otherwise this is identical to hardware_memlimit_get(MODE_COMPRESS).

The idea is to keep automatic thread count reasonable so that too high memory usage is avoided and, with 32-bit xz, running out of address space is avoided.

hardware_memlimit_mtenc_is_default()

bool hardware_memlimit_mtenc_is_default ( void )

extern

Returns true if the value returned by hardware_memlimit_mtenc_get() is a system-specific default value. coder.c uses this to ignore the default memlimit in case it's too small even for a single thread in multithreaded mode. This way the default limit will never make xz fail or affect the compressed output; it will only make xz reduce the number of threads.

hardware_memlimit_set()

void hardware_memlimit_set ( uint64_t new_memlimit, bool set_compress, bool set_decompress, bool set_mtdec, bool is_percentage )

extern

Set the memory usage limit. There are separate limits for compression, decompression (also includes –list), and multithreaded decompression. Any combination of these can be set with a single call to this function. Zero indicates resetting the limit back to the defaults. The limit can also be set as a percentage of installed RAM; the percentage must be in the range [1, 100].

hardware_memlimit_show()

void hardware_memlimit_show ( void )

extern

Display the amount of RAM and memory usage limits and exit.

hardware_threads_get()

uint32_t hardware_threads_get ( void )

extern

Get the maximum number of worker threads.

hardware_threads_is_mt()

bool hardware_threads_is_mt ( void )

extern

Returns true if multithreaded mode should be used for .xz compression. This can be true even if the number of threads is one.

hardware_threads_set()

void hardware_threads_set ( uint32_t threadlimit )

extern

Set the maximum number of worker threads. A special value of UINT32_MAX sets one thread in multi-threaded mode.