75 lines
3.1 KiB
C
75 lines
3.1 KiB
C
// SPDX-License-Identifier: 0BSD
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///////////////////////////////////////////////////////////////////////////////
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//
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/// \file hardware.h
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/// \brief Detection of available hardware resources
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//
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// Author: Lasse Collin
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//
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///////////////////////////////////////////////////////////////////////////////
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/// Initialize some hardware-specific variables, which are needed by other
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/// hardware_* functions.
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extern void hardware_init(void);
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/// Set the maximum number of worker threads.
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/// A special value of UINT32_MAX sets one thread in multi-threaded mode.
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extern void hardware_threads_set(uint32_t threadlimit);
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/// Get the maximum number of worker threads.
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extern uint32_t hardware_threads_get(void);
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/// Returns true if multithreaded mode should be used for .xz compression.
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/// This can be true even if the number of threads is one.
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extern bool hardware_threads_is_mt(void);
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/// Set the memory usage limit. There are separate limits for compression,
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/// decompression (also includes --list), and multithreaded decompression.
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/// Any combination of these can be set with a single call to this function.
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/// Zero indicates resetting the limit back to the defaults.
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/// The limit can also be set as a percentage of installed RAM; the
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/// percentage must be in the range [1, 100].
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extern void hardware_memlimit_set(uint64_t new_memlimit,
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bool set_compress, bool set_decompress, bool set_mtdec,
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bool is_percentage);
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/// Get the current memory usage limit for compression or decompression.
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/// This is a hard limit that will not be exceeded. This is obeyed in
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/// both single-threaded and multithreaded modes.
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extern uint64_t hardware_memlimit_get(enum operation_mode mode);
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/// This returns a system-specific default value if all of the following
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/// conditions are true:
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///
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/// - An automatic number of threads was requested (--threads=0).
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///
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/// - --memlimit-compress wasn't used or it was reset to the default
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/// value by setting it to 0.
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///
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/// Otherwise this is identical to hardware_memlimit_get(MODE_COMPRESS).
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///
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/// The idea is to keep automatic thread count reasonable so that too
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/// high memory usage is avoided and, with 32-bit xz, running out of
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/// address space is avoided.
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extern uint64_t hardware_memlimit_mtenc_get(void);
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/// Returns true if the value returned by hardware_memlimit_mtenc_get() is
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/// a system-specific default value. coder.c uses this to ignore the default
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/// memlimit in case it's too small even for a single thread in multithreaded
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/// mode. This way the default limit will never make xz fail or affect the
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/// compressed output; it will only make xz reduce the number of threads.
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extern bool hardware_memlimit_mtenc_is_default(void);
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/// Get the current memory usage limit for multithreaded decompression.
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/// This is only used to reduce the number of threads. This limit can be
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/// exceeded if the number of threads are reduce to one. Then the value
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/// from hardware_memlimit_get() will be honored like in single-threaded mode.
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extern uint64_t hardware_memlimit_mtdec_get(void);
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/// Display the amount of RAM and memory usage limits and exit.
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tuklib_attr_noreturn
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extern void hardware_memlimit_show(void);
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