diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/xz/xz.1 | 22 |
1 files changed, 14 insertions, 8 deletions
diff --git a/src/xz/xz.1 b/src/xz/xz.1 index f2c1ce35..6c8a52f5 100644 --- a/src/xz/xz.1 +++ b/src/xz/xz.1 @@ -4,7 +4,7 @@ .\" Authors: Lasse Collin .\" Jia Tan .\" -.TH XZ 1 "2024-01-23" "Tukaani" "XZ Utils" +.TH XZ 1 "2024-02-13" "Tukaani" "XZ Utils" . .SH NAME xz, unxz, xzcat, lzma, unlzma, lzcat \- Compress or decompress .xz and .lzma files @@ -799,8 +799,6 @@ in the single-threaded mode. It may vary slightly between .B xz versions. -Memory requirements of some of the future multithreaded modes may -be dramatically higher than that of the single-threaded mode. .IP \(bu 3 DecMem contains the decompressor memory requirements. That is, the compression settings determine @@ -809,6 +807,15 @@ The exact decompressor memory usage is slightly more than the LZMA2 dictionary size, but the values in the table have been rounded up to the next full MiB. .RE +.IP "" +Memory requirements of the multi-threaded mode are +significantly higher than that of the single-threaded mode. +With the default value of +.BR \-\-block\-size , +each thread needs 3*3*DictSize plus CompMem or DecMem. +For example, four threads with preset +.B \-6 +needs 660\(en670\ MiB of memory. .TP .BR \-e ", " \-\-extreme Use a slower variant of the selected compression preset level @@ -900,17 +907,16 @@ Using .I size less than the LZMA2 dictionary size is waste of RAM because then the LZMA2 dictionary buffer will never get fully used. -The sizes of the blocks are stored in the block headers, -which a future version of -.B xz -will use for multi-threaded decompression. +In multi-threaded mode, +the sizes of the blocks are stored in the block headers. +This size information is required for multi-threaded decompression. .IP "" In single-threaded mode no block splitting is done by default. Setting this option doesn't affect memory usage. No size information is stored in block headers, thus files created in single-threaded mode won't be identical to files created in multi-threaded mode. -The lack of size information also means that a future version of +The lack of size information also means that .B xz won't be able decompress the files in multi-threaded mode. .TP |