Date: Thu, 19 Aug 2004 02:28:05 GMT From: Suihong Liang <s2liang@uwaterloo.ca> To: freebsd-gnats-submit@FreeBSD.org Subject: kern/70649: system clock slows down when heavily loaded Message-ID: <200408190228.i7J2S5fv066240@www.freebsd.org> Resent-Message-ID: <200408190230.i7J2UN0k015908@freefall.freebsd.org>
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>Number: 70649
>Category: kern
>Synopsis: system clock slows down when heavily loaded
>Confidential: no
>Severity: serious
>Priority: high
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Thu Aug 19 02:30:23 GMT 2004
>Closed-Date:
>Last-Modified:
>Originator: Suihong Liang
>Release: 5.2.1
>Organization:
Univeristy of Waterloo
>Environment:
FreeBSD hurricane.cs.uwaterloo.ca 5.2.1-RELEASE FreeBSD 5.2.1-RELEASE #2: Fri Jul 2 16:25:54 GMT 2004 root@hurricane.cs.uwaterloo.ca:/usr/src/sys/i386/compile/ORIGIN i386
>Description:
It takes "SHORTER" time in scp a file while heavily loaded, in
fact, the receiver shows that it takes LONGER!
I think the kernel does not handle the system clock well when it is heavily loaded.
I've tried the built-in time, GNU time, and my simple home-brewed timer programs, same result was yielded.
>How-To-Repeat:
1. cpu workload program can be a infinite loop program.
2. In my testing, I run 32 instances of such workload programs.
3. Use command "time" to time the scp in an ethernet environment. Do NOT trust the time reported by scp.
4. I used the same set of 30 files (each of 100MB).
5. reboot the sender after each set of scp is done.
>Fix:
>Release-Note:
>Audit-Trail:
>Unformatted:
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