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| author | Lasse Collin <lasse.collin@tukaani.org> | 2024-01-23 18:29:28 +0200 |
|---|---|---|
| committer | Lasse Collin <lasse.collin@tukaani.org> | 2024-01-23 18:29:28 +0200 |
| commit | 6daa4d0ea46a8441f21f609149f3633158bf4704 (patch) | |
| tree | f8a3fd6fdc49b7eba8c421e3c944a02f8baaaf9c | |
| parent | CI: Use RISC-V filter when building with BCJ support. (diff) | |
| download | xz-6daa4d0ea46a8441f21f609149f3633158bf4704.tar.xz | |
xz: Use threaded mode by defaut (as if --threads=0 was used).
This hopefully does more good than bad:
+ It's faster by default.
+ Only the threaded compressor creates files that
can be decompressed in threaded mode.
- Compression ratio is worse, usually not too much though.
When it matters, -T1 must be used.
- Memory usage increases.
- Scripts that assume single-threaded mode but don't use -T1 will
possibly use too much resources, for example, if they run
multiple xz processes in parallel to compress multiple files.
- Output from single-threaded and multi-threaded compressors
differ but such changes could happen for other reasons too
(they just haven't happened since 5.0.0).
| -rw-r--r-- | src/xz/hardware.c | 6 | ||||
| -rw-r--r-- | src/xz/message.c | 4 | ||||
| -rw-r--r-- | src/xz/xz.1 | 9 |
3 files changed, 16 insertions, 3 deletions
diff --git a/src/xz/hardware.c b/src/xz/hardware.c index c6948821..73bac4a9 100644 --- a/src/xz/hardware.c +++ b/src/xz/hardware.c @@ -15,7 +15,7 @@ /// Maximum number of worker threads. This can be set with /// the --threads=NUM command line option. -static uint32_t threads_max = 1; +static uint32_t threads_max; /// True when the number of threads is automatically determined based /// on the available hardware threads. @@ -334,5 +334,9 @@ hardware_init(void) memlimit_mt_default = mem_ceiling; #endif + // Enable threaded mode by default. xz 5.4.x and older + // used single-threaded mode by default. + hardware_threads_set(0); + return; } diff --git a/src/xz/message.c b/src/xz/message.c index b94a0eba..7756b5b2 100644 --- a/src/xz/message.c +++ b/src/xz/message.c @@ -1022,8 +1022,8 @@ message_help(bool long_help) " does not affect decompressor memory requirements")); puts(_( -" -T, --threads=NUM use at most NUM threads; the default is 1; set to 0\n" -" to use as many threads as there are processor cores")); +" -T, --threads=NUM use at most NUM threads; the default is 0 which uses\n" +" as many threads as there are processor cores")); if (long_help) { puts(_( diff --git a/src/xz/xz.1 b/src/xz/xz.1 index 3c09309b..950585f8 100644 --- a/src/xz/xz.1 +++ b/src/xz/xz.1 @@ -1303,6 +1303,15 @@ meet this condition, but files compressed in single-threaded mode don't even if .BI \-\-block\-size= size has been used. +.IP "" +The default value for +.I threads +is +.BR 0 . +In +.B xz +5.4.x and older the default is +.BR 1 . . .SS "Custom compressor filter chains" A custom filter chain allows specifying |