How can I know the number of current users in the system?

[Wei Xiaoliang]

Hi every one,
    I have a problem not clear: Is there any counter for the user number
in linux?
I want to do anexperiment which will get the number of current user in
the system and try fair-share scheduling based on it. I read the sys.c
and user.c but cannot find a counter for it. Is there any counter for
this things?

    If no, where can I put the inc instruct and dec instruct  or the
counter? in the uid_hash_insert and uid_hash_remove?
    Thank you!
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Xiaoliang (David) Wei                    Graduate Student in CS, Caltech
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Mail:     Xiaoliang Wei, 256-80 Caltech, Pasadena, CA 91125, U.S.A.
WWW: http://www.cs.caltech.edu/~weixl    http://166.111.69.241/~wxl
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