diff options
Diffstat (limited to 'src/xz/hardware.h')
-rw-r--r-- | src/xz/hardware.h | 49 |
1 files changed, 43 insertions, 6 deletions
diff --git a/src/xz/hardware.h b/src/xz/hardware.h index 4fae61815656..2bb3d7ba9493 100644 --- a/src/xz/hardware.h +++ b/src/xz/hardware.h @@ -16,22 +16,59 @@ extern void hardware_init(void); /// Set the maximum number of worker threads. +/// A special value of UINT32_MAX sets one thread in multi-threaded mode. extern void hardware_threads_set(uint32_t threadlimit); /// Get the maximum number of worker threads. extern uint32_t hardware_threads_get(void); +/// Returns true if multithreaded mode should be used for .xz compression. +/// This can be true even if the number of threads is one. +extern bool hardware_threads_is_mt(void); -/// Set the memory usage limit. There are separate limits for compression -/// and decompression (the latter includes also --list), one or both 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]. + +/// 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]. extern void hardware_memlimit_set(uint64_t new_memlimit, - bool set_compress, bool set_decompress, bool is_percentage); + bool set_compress, bool set_decompress, bool set_mtdec, + bool is_percentage); /// 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. extern uint64_t hardware_memlimit_get(enum operation_mode mode); +/// 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. +extern uint64_t hardware_memlimit_mtenc_get(void); + +/// 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. +extern bool hardware_memlimit_mtenc_is_default(void); + +/// 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. +extern uint64_t hardware_memlimit_mtdec_get(void); + /// Display the amount of RAM and memory usage limits and exit. extern void hardware_memlimit_show(void) lzma_attribute((__noreturn__)); |