Engaged Clown
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1. Changes in RAR compression:
a) RAR general compression algorithm is optimized for better
utilization of several processor cores. While some speed gain
is possible even in single processor mode, best results
are achieved in multi-core environment.
Speed gain depends on data type and average file size.
Several cores are utilized more efficiently when compressing
large files.
b) we had to increase memory requirements to achieve higher
compression speed. General RAR compression algorithm allocates
about 120 MB comparing to 40 MB in WinRAR 4.11;
c) RAR text compression algorithm cannot utilize several CPU cores
efficiently, so its performance in multiprocessor environment
is much lower than for general algorithm. Also its decompression
speed is much lower than in general algorithm regardless of
CPU number. So we decided to disable the text algorithm by default.
If you need maximum possible compression ratio for plain text data
regardless of speed, you can enable the text compression
in "Advanced compression parameter" dialog. Press "Compression..."
button on "Advanced" page of archiving dialog to access it.
You can also change this option permanently in default compression
profile;
In the command line mode the text compression can be enabled
with -mct switch;
d) "Fastest" (-m1) compression mode also supports several processor
cores now. In 4.11 it could use only a single processor core.
2. RAR general decompression algorithm speed is slightly improved,
though not to same extent as RAR compression. RAR decompression
is not able to use several processor cores, so its performance
does not depend on a number of cores.
3. Changes in ZIP compression:
a) now ZIP compression supports several processor cores resulting
in noticeably higher performance in multi-core environment.
Single CPU ZIP compression is also faster than in 4.11;
b) memory use for ZIP compression is increased to about 15 MB.
4. Recovery volume creating and processing can use several CPU cores
resulting in higher speed. Though, typically hard drive seek speed
is a limiting factor for recovery volumes, so this gain is most
noticeable when working with solid state drive.
5. Now the allowed value for -mt switch is 1 - 32,
not 0 - 16 as before.
6. "Find files" command can search data in 7-Zip archives.
Previously "Find files" did not support .7z archive format.
7. Windows 2000 is not supported by WinRAR and WinRAR self-extracting
modules anymore.
8. "Save current settings" button in "Advanced SFX options" dialog
is now available only when converting an existing archive to SFX.
Options saved with this button are applied only to convert to SFX
operation.
If you create or update SFX archive, only SFX options stored
in default compression profile are used. Options saved
in "Advanced SFX options" dialog are ignored for these operations. |
