Onboard System Memory Cache May Affect Profile Times (73035)
The information in this article applies to:
- Microsoft Source Profiler for MS-DOS
- Microsoft Source Profiler for Windows
- Microsoft Source Profiler for OS/2
This article was previously published under Q73035
The information in this article is included in the documentation starting
with Visual C++ 5.0. Look there for future revisions.
SUMMARY
The Microsoft Source Profiler may display erratic execution times on any
system with an Intel 80386 or 80486 processor that has a built-in memory
cache. This is noted in the Operating-System Notes in the "Microsoft Source
Profiler User's Guide" and in the Profiler online help. The only real
workaround is to disable the cache, because there is no way to control what
is cached and what is not cached.
MORE INFORMATION
The erratic profile results are caused by the way a memory cache of
this type operates. If code from the program being profiled is in the
cache, the execution times will be less than normal. On the other
hand, it's likely that the cache will be dominated by the Profiler
itself, since the instructions from the Profiler's own code will
usually be in the cache. This may then result in increased times for
the program being profiled. Caching will also affect small programs
more than large ones due to the successful hit rate in the cache.
Because memory caching hinders accurate profiling, a system without a
cache should be used while profiling to ensure the most reliable
times. In any case, the overall effect of a cached system should be
that it runs faster, so it should not be necessary to consider this
net gain when profiling.
| Modification Type: | Major | Last Reviewed: | 11/17/2003 |
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| Keywords: | kb16bitonly KB73035 |
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