| 1 | <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
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| 2 | <HTML>
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| 3 | <HEAD>
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| 4 | <META http-equiv="Content-Type" content="text/html; charset=Windows-1252">
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| 5 | <TITLE>b (Benchmark) command</TITLE>
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| 6 | <LINK href="style.css" rel="stylesheet" type="text/css">
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| 7 | </HEAD>
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| 8 |
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| 9 | <BODY>
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| 10 |
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| 11 | <H1>b (Benchmark) command</H1>
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| 12 |
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| 13 | <P>Measures speed of the CPU and checks RAM for errors.</P>
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| 14 |
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| 15 | <H4>Syntax</H4>
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| 16 |
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| 17 | <PRE class="syntax">
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| 18 | b [number_of_iterations] [-mmt{N}] [-md{N}] [-mm={Method}]
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| 19 | </PRE>
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| 20 |
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| 21 | <P>There are two tests:<P>
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| 22 | <OL>
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| 23 | <LI>Compressing with LZMA method
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| 24 | <LI>Decompressing with LZMA method
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| 25 | </OL>
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| 26 |
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| 27 | <P>The benchmark shows a rating in MIPS (million instructions per second).
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| 28 | The rating value is calculated from the measured CPU speed and it
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| 29 | is normalized with results of Intel Core 2 CPU with multi-threading option
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| 30 | switched off. So if you have Intel Core 2 Duo,
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| 31 | rating values must be close to real CPU frequency.</P>
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| 32 |
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| 33 | <P>You can change the upper dictionary size to increase memory usage by -md{N} switch.
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| 34 | Also, you can change the number of threads by -mmt{N} switch.</P>
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| 35 |
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| 36 | <P>The <B>Dict</B> column shows dictionary size. For example, 21 means 2^21 = 2 MB.</P>
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| 37 |
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| 38 | <P>The <B>Usage</B> column shows the percentage of time the processor is working.
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| 39 | It's normalized for a one-thread load. For example, 180% CPU Usage for 2 threads
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| 40 | can mean that average CPU usage is about 90% for each thread.</P>
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| 41 |
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| 42 | <P>The <B>R / U</B> column shows the rating normalized for 100% of CPU usage.
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| 43 | That column shows the performance of one average CPU thread.</P>
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| 44 |
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| 45 | <P><B>Avr</B> shows averages for different dictionary sizes.</P>
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| 46 | <P><B>Tot</B> shows averages of the compression and decompression ratings.</P>
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| 47 |
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| 48 | <P>Compression speed and rating strongly depend on memory (RAM) latency.
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| 49 |
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| 50 | <P>Decompression speed and rating strongly depend on the integer performance of the CPU.
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| 51 | For example, the Intel Pentium 4 has big branch
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| 52 | misprediction penalty (which is an effect of its long pipeline) and pretty slow
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| 53 | multiply and shift operations. So, the Pentium 4 has pretty low decompressing ratings.</P>
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| 54 |
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| 55 | <P>You can run a CRC calculation benchmark by specifying -mm=crc.
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| 56 | That test shows the speed of CRC calculation in MB/s. The first column shows the size of the block.
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| 57 | The next column shows the speed of CRC calculation for one thread. The other columns are results
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| 58 | for multi-threaded CRC calculation.</P>
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| 59 |
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| 60 |
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| 61 | <H4>Examples</H4>
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| 62 |
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| 63 | <PRE class="example">
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| 64 | 7z b
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| 65 | </PRE>
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| 66 | runs benchmarking.
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| 67 |
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| 68 | <PRE class="example">
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| 69 | 7z b -mmt1 -md26
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| 70 | </PRE>
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| 71 | runs benchmarking with one thread and 64 MB dictionary.
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| 72 |
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| 73 | <PRE class="example">
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| 74 | 7z b 30
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| 75 | </PRE>
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| 76 | <P>runs benchmarking with default settings for 30 iterations.</P>
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| 77 |
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| 78 | </BODY>
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| 79 | </HTML>
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