Date: Tue, 27 Feb 2007 04:54:33 +0000 (UTC) From: Bruce Evans <bde@FreeBSD.org> To: src-committers@FreeBSD.org, cvs-src@FreeBSD.org, cvs-all@FreeBSD.org Subject: cvs commit: src/usr.bin/netstat if.c Message-ID: <200702270454.l1R4sXGe003975@repoman.freebsd.org>
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bde 2007-02-27 04:54:33 UTC
FreeBSD src repository
Modified files:
usr.bin/netstat if.c
Log:
Use a periodic itimer instead of repeated calls to alarm() in
sidewaysintpr(). This increases the accuracy of the per-interval
counts when they are interpreted as rates. Repeated calls to alarm(n)
give an average interval that is about 2 ticks larger than n and has
a large variance. Periodic itimers normally get the average almost
right but have similarly large variance (due to scheduling delays).
Statistics utilities should use clock_gettime() to determine the
actual interval, but it is still useful to maximize the accuracy of
the interval, especially for cases like netstat -w where counts are
displayed so the program cannot hide the inaccuracy in a rate
conversion.
Revision Changes Path
1.67 +9 -7 src/usr.bin/netstat/if.c
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