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List:       freebsd-smp
Subject:    Re: Functional interrupt-thread based SMPng code is now available
From:       Poul-Henning Kamp <phk () critter ! freebsd ! dk>
Date:       2000-08-04 8:30:24
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In message <20000803164632.B30009@wantadilla.lemis.com>, Greg Lehey writes:
>I now have interrupt threads running here on a single processor Intel
>machine.  Diffs against today's -CURRENT are at
>http://people.freebsd.org/~grog/patches4.gz.
>
>This code still needs a lot of work, of course.  In particular,
>
>1.  There's no alpha MD support.
>2.  There's no Intel SMP support.
>3.  There are various minor things which need fixing.  For example:
>    - CPU time usage doesn't work correctly: vmstat and top both show
>      100% system CPU usage, no user time, no idle.  ps shows that the
>      rtc interrupt (irq8) is using between 80% and 100% of CPU time,
>      and the interrupt processes don't accumulate CPU time.  I'll
>      look at these in the near future.

This is because irq8 is the statclock() interrupt which charges ticks to
system/user time for processes.  It always charges curproc.

It might be a better and more efficient thing to use use the TSC/PCC to
account cpu time with, but since we don't have that on i386/i486 we
would probably need to retain the old statclock code as a kernel option.

--
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD coreteam member | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.


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