Compressing and Uncompressing Files Cause File Cache to Grow (164260)
The information in this article applies to:
- Microsoft Windows NT Workstation 4.0
- Microsoft Windows NT Server 4.0
This article was previously published under Q164260 SYMPTOMS
When you compress or uncompress big files, the performance of the
interactive processes may suffer. This happens when the files are bigger
than the physical memory of the computer.
All three of the following utilities capable of compressing or
uncompressing files in Windows NT show this behavior:
COMPACT utility (Compact.exe)
File Manager (Winfile.exe)
Windows NT Explorer (Explorer.exe)
When you run performance monitor during compression you will see that the
cache (Memory: Cache Bytes) is very large (between 50 and 90 percent of the
physical memory) and the working sets of the processes (Process: Working
Set, Instance _Total) are reduced.
MORE INFORMATION
The CreateFile API has a flag FILE_FLAG_SEQUENTIAL_SCAN that is especially
useful when working on files in a sequential manner. It tells Cache Manager
not to grow the file cache when requests for this handle arrive. Therefore,
Memory Manager does not have to shrink the application's working set to
accommodate the bigger cache.
None of the three utilities used this flag when opening the files for
compression or decompression.
STATUS
Microsoft has confirmed this to be a problem in Windows NT version 4.0.
This problem was corrected in the latest Microsoft Windows NT 4.0 U.S. Service
Pack. For information on obtaining the service pack, query on the following word
in the Microsoft Knowledge Base (without the spaces):
| Modification Type: | Major | Last Reviewed: | 8/8/2001 |
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| Keywords: | kbbug KB164260 |
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