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-   -   Utterly surreal OS bug (https://www.mersenneforum.org/showthread.php?t=14899)

fivemack 2011-01-19 00:03

Utterly surreal OS bug
 
[code]

nfsslave2@cow:/home/nfsworld/2+956/linalg$ ps -L 11743
PID LWP TTY STAT TIME COMMAND
11743 11743 ? Rl 9645:56 ../../msieve-svn/trunk/msieve-td130 -v -nc -t 4
11743 21509 ? Rl 8653:20 ../../msieve-svn/trunk/msieve-td130 -v -nc -t 4
11743 21510 ? Rl 9014:08 ../../msieve-svn/trunk/msieve-td130 -v -nc -t 4
11743 21515 ? Rl 9043:40 ../../msieve-svn/trunk/msieve-td130 -v -nc -t 4
nfsslave2@cow:/home/nfsworld/2+956/linalg$ ps 11743
PID TTY STAT TIME COMMAND
11743 ? Rl 24260266:53 ../../msieve-svn/trunk/msieve-td130 -v -nc -t 4
[/code]

(and whilst the times reported by -L go up at a rate of about one minute per minute, the one reported by 'ps' on its own stays at that ridiculous value)

I don't think I need to do anything about this, but it's most peculiar. Process 11743 also doesn't appear in 'top'.

xilman 2011-01-19 07:42

[QUOTE=fivemack;247263][code]

nfsslave2@cow:/home/nfsworld/2+956/linalg$ ps -L 11743
PID LWP TTY STAT TIME COMMAND
11743 11743 ? Rl 9645:56 ../../msieve-svn/trunk/msieve-td130 -v -nc -t 4
11743 21509 ? Rl 8653:20 ../../msieve-svn/trunk/msieve-td130 -v -nc -t 4
11743 21510 ? Rl 9014:08 ../../msieve-svn/trunk/msieve-td130 -v -nc -t 4
11743 21515 ? Rl 9043:40 ../../msieve-svn/trunk/msieve-td130 -v -nc -t 4
nfsslave2@cow:/home/nfsworld/2+956/linalg$ ps 11743
PID TTY STAT TIME COMMAND
11743 ? Rl 24260266:53 ../../msieve-svn/trunk/msieve-td130 -v -nc -t 4
[/code](and whilst the times reported by -L go up at a rate of about one minute per minute, the one reported by 'ps' on its own stays at that ridiculous value)

I don't think I need to do anything about this, but it's most peculiar. Process 11743 also doesn't appear in 'top'.[/QUOTE]I saw exactly the same thing when doing the LA for a c178 recently. I believe that the author of top(1) didn't expect a single process to clock up so much time and a variable overflowed. I'm almost, but not quite, tempted to check the source of top(1) to find out. The underlying bug is, presumably, in the code that implements the /proc/*/stat interface.


Paul


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