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Date:      Tue, 05 Feb 2002 21:37:30 +0100
From:      Poul-Henning Kamp <phk@critter.freebsd.dk>
To:        John Polstra <jdp@polstra.com>
Cc:        hackers@freebsd.org
Subject:   Re: A question about timecounters 
Message-ID:  <93251.1012941450@critter.freebsd.dk>
In-Reply-To: Your message of "Tue, 05 Feb 2002 12:28:49 PST." <200202052028.g15KSna04510@vashon.polstra.com> 

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In message <200202052028.g15KSna04510@vashon.polstra.com>, John Polstra writes:

>After 25 minutes testing that with NTIMECOUNTER=50000, I haven't
>gotten any microuptime messages.  So it appears that my problem was
>just that the current timecounter wrapped all the way around the ring
>while microuptime was interrupted, due to the high HZ value and the
>heavy interrupt load.  I'm sorry I didn't try this sooner, when you
>suggested it.
>
>After lunch I'll try NTIMECOUNTER=HZ (10000 in my case).  That sounds
>like a nice default value to me.

Yup, if we preempt things for more than a second we have other problems
too I think.

My fault for not letting it depend in HZ in the first place.

>It would be interesting to see whether this same fix also works in
>-current.  I'm not sure yet if I can test that here or not.  I haven't
>tried building my netgraph module under -current yet.

Well, either way I will commit the volatile and this NTIMECOUNTER to
-current now, it's certainly better than what is there now.

Thanks for the help, I owe you one at BSDcon!

Poul-Henning

Ohh, and btw: do I need to say that I'm dying to know what the heck
you are doing with that box ?  :-)

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

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