Make the default memory usage limit 40 % of RAM for both

compressing and decompressing. This should be OK now that
xz automatically scales down the compression settings if
they would exceed the memory usage limit (earlier, the limit
for compression was increased to 90 % because low limit broke
scripts that used "xz -9" on systems with low RAM).

Support spcifying the memory usage limit as a percentage
of RAM (e.g. --memory=50%).

Support --threads=0 to reset the thread limit to the default
value (number of available CPU cores). Use UINT32_MAX instead
of SIZE_MAX as the maximum in args.c. hardware.c was already
expecting uint32_t value.

Cleaned up the output of --help and --long-help.

1 files changed, 7 insertions, 11 deletions

diff --git a/src/xz/process.c b/src/xz/process.c
index 4e682d7d..7a3c4149 100644
--- a/src/xz/process.c
+++ b/src/xz/process.c
@@ -152,15 +152,12 @@ coder_set_compression_settings(void)
 	// If using --format=raw, we can be decoding. The memusage function
 	// also validates the filter chain and the options used for the
 	// filters.
+	const uint64_t memory_limit = hardware_memlimit_get();
 	uint64_t memory_usage;
-	uint64_t memory_limit;
-	if (opt_mode == MODE_COMPRESS) {
+	if (opt_mode == MODE_COMPRESS)
 		memory_usage = lzma_raw_encoder_memusage(filters);
-		memory_limit = hardware_memlimit_encoder();
-	} else {
+	else
 		memory_usage = lzma_raw_decoder_memusage(filters);
-		memory_limit = hardware_memlimit_decoder();
-	}
 
 	if (memory_usage == UINT64_MAX)
 		message_fatal("Unsupported filter chain or filter options");
@@ -286,17 +283,17 @@ coder_init(void)
 		switch (opt_format) {
 		case FORMAT_AUTO:
 			ret = lzma_auto_decoder(&strm,
-					hardware_memlimit_decoder(), flags);
+					hardware_memlimit_get(), flags);
 			break;
 
 		case FORMAT_XZ:
 			ret = lzma_stream_decoder(&strm,
-					hardware_memlimit_decoder(), flags);
+					hardware_memlimit_get(), flags);
 			break;
 
 		case FORMAT_LZMA:
 			ret = lzma_alone_decoder(&strm,
-					hardware_memlimit_decoder());
+					hardware_memlimit_get());
 			break;
 
 		case FORMAT_RAW:
@@ -436,8 +433,7 @@ coder_run(file_pair *pair)
 				// Figure out how much memory it would have
 				// actually needed.
 				uint64_t memusage = lzma_memusage(&strm);
-				uint64_t memlimit
-						= hardware_memlimit_decoder();
+				uint64_t memlimit = hardware_memlimit_get();
 
 				// Round the memory limit down and usage up.
 				// This way we don't display a ridiculous