the fastest among popular archivers

Transcription

1 the fastest among popular archivers July, 2011

2 Contents 3 Introduction 4 Principles of acceleration 4 4 Preparation 4 PC configuration for tests 5 Virtual disk 5 Data 6 Archivers 6 Clocking 6 Testing 7 Quick Compression Test. Minimum Compression 7 Compression Ratio Test. Maximum Compression 8 Results 8 Quick Compression Test. Minimum Compression 8 Compression Ratio Test. Maximum Compression 9 Conclusion 2

3 Hamster Free Zip Archiver compresses files twice as fast as other popular archivers at the same compression level. Introduction Time Required For Compression Data In Seconds Nowadays, we are able to transmit thousands of times more data in a given amount of time than 10 years ago. Storage capacities of portable data media have increased to terabytes. Moreover, the capacity of data transmission channels and the volume of data media have been growing rapidly. It might seem that archivers are becoming obsolete. However, in spite of growing processing powers, compression and decompression speed and the problem of saving energy are still important. There is not much difference between archivers with regard to the compression ratio. Most archiver comparisons demonstrate that the various algorithms differ only by a few tenths of a percent. The difference between the winner and the worst performer is no more than 1-2%. We think few people consider data compression speed. However, if compression takes less time, processors require less real time for compression and, consequently, consume less power. Thus, by accelerating information processing, we make it more energy efficient. We have selected the ZIP algorithm for speed optimization, since it is the most common and internationally recognized format of lossless compressed data transmission. Moreover, nearly all archivers support ZIP unpacking, so even those who are not yet using Hamster Free ZIP Archiver will be able to retrieve archived files. The result of our work can be seen in the figure at the beginning of the document, Introduction 3

4 and the method by which we achieved this result will be set forth below. This result is achieved through better task multisequencing and the use of HyperThreading technology. Principles of acceleration The general concept is to break the common data stream down into fragments and compress them in different streams. Intel processor technologies are used to accelerate the process. In each stream, compression is performed with its own dictionary. This may result in a certain reduction of the compression ratio due to the use of multiple dictionaries. To compare compression speed, 3 iterations will be performed to obtain a reliable average value. During each iteration, specially prepared data will be compressed by the archivers, first at the minimum compression ratio (so-called quick compression), and then at the maximum compression ratio. In the end, a table of average results will be prepared; conclusions about the test will be drawn on the basis of these results. Preparation The preparation consists of installing a virtual disk on a PC, installing archivers, saving 1 gigabyte of data on the virtual disk, and setting up a clocking utility. PC configuration for tests A modern computer with four physical central processors supporting HyperThreading technology was used for the test. We recommend using a computer with at least 4 GB of RAM. The computer we used for the test had the following configuration: CPU=Intel Core i GHz, 4 physical cores, 8 logical cores (HyperThreading) RAM=12 Gb -- 3 channel 3*4Gb OS=Windows 7 Ultimate SP1 x64 4

5 Virtual disk To avoid problems related to the hard drive being accessed by the OS and other programs, let us use a virtual disk. We will use a program which creates a virtual disk in the memory. Random access memory has greater processing capacity, and a critical load of its interfaces during testing is much less likely than it is with a hard drive. Preparation 1. Download a free version of the virtual drive software 2. Install the downloaded Data Ram RAMDisk 3. Create a virtual disk with a size of 1.5 GB 4. Restart the PC Data At the present time, it makes sense to use archivers for compression of programs (convenient for data backups and software distribution) and alphanumeric data. Photographic, audio and video formats already use lossy compression which is inherently much more effective than ZIP. This test involves working with alphanumeric data on the basis of the first gigabyte of English Wikipedia data as of March 1, This set of data is used for a compression quality test known among specialists. Preparation 1. Download test data (first gigabyte of Wikipedia.org data) 2. Download the pmd archive unpacker 3. Extract the data to your virtual disk by executing the command ppmd d enwik9.pmd in the command line 4. Rename the alphanumeric data TestData for convenience Thus, we have obtained the data for the test. 5

6 Archivers We will test the 4 most popular archivers WinZip, WinRar, 7z, and Hamster Free Zip Archiver. In order to determine algorithm speeds more precisely, we will perform 3 tests. Preparation 1. Hamster Free Zip Archiver. Download the archiver from the official website. Save it in a folder to run from the command line. 2. 7z archiver. Download the software from the official web-page. This is 7-Zip Command Line Version. Save it in a folder to run from the command line. 3. WinRAR v Download the archiver from the official website. Install it. 4. WinZip v.15. Download the archiver from the official website. Install it. Clocking To measure the time required for data compression by 7-zip and Hamster Free Zip Archiver, we used the 7-Benchmark utility. The Global Time parameter was applied. The compression time of WinZip and WinRAR was measured using a stopwatch. Even in the case of a 1-second error on the part of the testing specialist in determining the beginning and the end of compression, the absolute inaccuracy of 2 seconds will not be of great importance, since a relative inaccuracy of will give an idea of the level of an algorithm s speed. Testing Each iteration of the test included two testing phases for quick compression and maximal compression by each of the four archivers. Let us evaluate the speed for both variants the quickest compression and the best compression. 6

7 Quick Compression Test. Minimum Compression Hamster Free Zip Archiver Test Type hfza.exe a 2 z:\1.zip z:\testdata in the command line 7z Archiver Test Run 7-Benchmark Type 7za.exe a -mx1 -mfb=3 -mpass=1 out_arch.zip z:\testdata in the command line WinRAR v.4.01 Test Compress alphanumeric data using the fastest compression mode WinZip v.15 Test Compress alphanumeric data using the Super fast compression mode Compression Ratio Test. Maximum Compression Hamster Free Zip Archiver Test Type hfza.exe 9 z:\1.zip z:\testdata in the command line. 7z Archiver Test Run 7-Benchmark Type 7za.exe a mx9 -mfb=3 -mpass=1 out_arch.zip z:\testdata in the command line WinRAR v.4.01 Test Compress alphanumeric data using the Best compression mode WinZip v.15 Test Compress alphanumeric data using the Best compression mode 7

8 Results The results are presented in tables as average readings of the three iterations and expressed in absolute and relative figures for convenience. Quick Compression Test. Minimum Compression Archiver Hamster Free Zip Archiver Amount Compression time, in Compression options of data, in bytes seconds Amount of Compression data time in percents ,33 100,00% 100,00% 7zip v mx ,76 104,66% 276,10% WinRAR v.4.01 "fastest" ,00 100,37% 225,08% WinZip v.15 "Super fast" ,00 100,34% 278,67% Compression Ratio Test. Maximum Compression Archiver Compression options Amount of data, in bytes Compression time, in seconds Amount of Compression data time in percents Hamster Free Zip Archiver ,30 100,00% 100% 7zip v mx ,57 93,67% 7990% WinRAR v.4.01 "best" ,00 97,20% 434% WinZip v.15 "Best" ,00 97,19% 427% With a minor difference in compression quality (and with even better compression quality in comparison to 7z), Hamster Free Zip Archiver performs compression twice as fast. 8

9 Conclusion HamsterSoft is currently improving both the speed and quality of compression. We are planning to optimize the file decompression process as well. We have discovered multiple possibilities for further optimization during our work. In fact, only a small part has been re-worked, but all our objectives have been met. There is still potential for further optimization, and it may be possible to increase the speed and the compression ratio by percent. The possibilities of multi-stream compression in some usage scenarios could be very much in demand. If the resources are available, such functionality might be implemented within 1-2 months. ZIP decompression speed will then increase by an average of: (N-1)* 50%, where N is the number of processor cores This means a 50% increase in speed for two-core systems, and a 150% increase for fourcore systems. It should be noted that initially the implementation will only be available for multifile archives. Afterwards, a version for one-file archives might be developed, provided that the archives are created in our multi-stream mode. The archive will still be fully compatible with the ZIP standard, i.e. they will be able to be decompressed by other programs. Conclusion 9

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