b (Benchmark) command
Measures speed of the CPU and checks RAM for errors.
Syntax
b [number_of_iterations] [-mmt{N}] [-md{N}] [-mm={Method}]
There are two tests:
- Compressing with LZMA method
- Decompressing with LZMA method
The benchmark shows a rating in MIPS (million instructions per second). The rating value is calculated from the measured CPU speed and it is normalized with results of Intel Core 2 CPU with multi-threading option switched off. So if you have Intel Core 2 Duo, rating values must be close to real CPU frequency.
You can change the upper dictionary size to increase memory usage by -md{N} switch. Also, you can change the number of threads by -mmt{N} switch.
The Dict column shows dictionary size. For example, 21 means 2^21 = 2 MB.
The Usage column shows the percentage of time the processor is working. It's normalized for a one-thread load. For example, 180% CPU Usage for 2 threads can mean that average CPU usage is about 90% for each thread.
The R / U column shows the rating normalized for 100% of CPU usage. That column shows the performance of one average CPU thread.
Avr shows averages for different dictionary sizes.
Tot shows averages of the compression and decompression ratings.
Compression speed and rating strongly depend on memory (RAM) latency.
Decompression speed and rating strongly depend on the integer performance of the CPU. For example, the Intel Pentium 4 has big branch misprediction penalty (which is an effect of its long pipeline) and pretty slow multiply and shift operations. So, the Pentium 4 has pretty low decompressing ratings.
You can run a CRC calculation benchmark by specifying -mm=crc. That test shows the speed of CRC calculation in MB/s. The first column shows the size of the block. The next column shows the speed of CRC calculation for one thread. The other columns are results for multi-threaded CRC calculation.
With -mm=* switch you can run a complex benchmark. It tests hash calculation methods, compression and encryption codecs of 7-Zip. Note that the tests of LZMA have big weight in "total" results. And the results are normilized with AMD K8 cpu in complex benchmark.
Examples
7z bruns benchmarking.
7z b -mmt1 -md26runs benchmarking with one thread and 64 MB dictionary.
7z b 30
runs benchmarking with default settings for 30 iterations.
7z b -mm=*
runs complex 7-Zip benchmark.
Other documents on this site:
- 7-Zip Manual /7zC.txt
- 7-Zip Manual /readme.txt
- 7-Zip Manual /copying.txt
- 7-Zip Manual /lzma.txt
- 7-Zip Manual /Methods.txt
- 7-Zip Manual /unRarLicense.txt
- 7-Zip Manual /License.txt
- 7-Zip Manual /src-history.txt
- 7-Zip Manual /7zFormat.txt
- 7-Zip Start Page
- Menu Items and Shortcut Keys
- 7-Zip File Manager
- Benchmark
- Options Dialog Box
- About Dialog Box
- Plugins
- Extract Dialog Box
- 7-Zip Plugin
- Add to Archive Dialog Box
- Exit Codes from 7-Zip
- Command Line Version User's Guide
- Command Line Syntax
- -y (assume Yes on all queries) switch
- -so (write data to stdout) switch
- -ai (Include archive filenames) switch
- -scc (Set charset for console input/output) switch
- -w (set Working directory) switch
- -bb (Set output log level) switch
- -sni (Store NT security information) switch
- -t (set Type of archive) switch
- -ssc (Set Sensitive Case mode) switch
- -ssw (Compress files open for writing) switch
- -stx (Exclude archive type) switch
- -si (read data from stdin) switch
- -sns (Store NTFS alternate Streams) switch
- -spf (Use fully qualified file paths) switch
- -- (Stop switches parsing) switch
- -x (Exclude filenames) switch
- Command Line Switches
- -ax (Exclude archive filenames) switch
- -r (Recurse subdirectories) switch
- -sfx (Create SFX archive) switch
- -i (Include filenames) switch
- -slp (Set Large Pages mode) switch
- -an (Disable parsing of archive_name) switch
- -stl (Set archive timestamp from the most recently modified file) switch
- -sa (set Archive name mode) switch
- -scrc (Set hash function) switch
- -ao (Overwrite mode) switch
- -o (set Output directory) switch
- -u (Update options) switch
- -m (Set compression Method) switch
- -spf (Use fully qualified file paths) switch
- -scs (Set charset for list files) switch
- -p (set Password) switch
- -slt (Show technical information) switch
- -sdel (Delete files after including to archive) switch
- -v (Create Volumes) switch
- d (Delete) command
- rn (Rename) command
- b (Benchmark) command
- l (List contents of archive) command
- e (Extract) command
- Command Line Commands
- a (Add) command
- t (Test integrity of archive) command
- u (Update) command
- h (Hash) command
- x (Extract with full paths) command
- Performance
- Thanks
- Frequently Asked Questions (FAQ)
- 7z Format
- General Information
- License for use and distribution
- Supported formats