xz: Add --memlimit-mt-decompress along with a default limit value.

--memlimit-mt-decompress allows specifying the limit for
multithreaded decompression. This matches memlimit_threading in
liblzma. This limit can only affect the number of threads being
used; it will never prevent xz from decompressing a file. The
old --memlimit-decompress option is still used at the same time.

If the value of --memlimit-decompress (the default value or
one specified by the user) is less than the value of
--memlimit-mt-decompress , then --memlimit-mt-decompress is
reduced to match --memlimit-decompress.

Man page wasn't updated yet.

1 files changed, 11 insertions, 6 deletions

diff --git a/src/xz/hardware.h b/src/xz/hardware.h
index 4fae6181..cefd7d10 100644
--- a/src/xz/hardware.h
+++ b/src/xz/hardware.h
@@ -22,16 +22,21 @@ extern void hardware_threads_set(uint32_t threadlimit);
 extern uint32_t hardware_threads_get(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.
 extern uint64_t hardware_memlimit_get(enum operation_mode mode);
 
+/// Get the current memory usage limit for multithreaded decompression.
+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__));