The question of why top/ps incorrectly reporting process execution
times came up in Karim and Michel's presentation at Usenix, and then
again during the Linux BOF (with a question from a U. Washington
person whose name I didn't get).
Although Linus briefly summarized the problem, I thought Linux folks
would be interested in a complete description and suggested solution.
The problem, exploit programs that demonstrate it, and a fix were all
described by McCanne and Torek in '93 (ironically, at *Usenix*, see
below for complete reference). The source of the problem is (as Linus
briefly described at the BOF) due to timer-driven programs interacting
with the profiling timers; McCanne and Torek provide details.
Seems like a good opportunity for some Linux hacker to implement a fix
based on prior work.
-John Heidemann
[McCanne93b]
Steve McCanne and Chris Torek.
A Randomized Sampling Clock for CPU Utilization Estimation and Code Profiling.
In USENIX Conference Proceedings, San Diego, CA, USENIX.
January, 1993.
<ftp://ftp.ee.lbl.gov/papers/statclk-usenix93.ps.Z>.
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