Date: Mon, 29 Nov 1999 12:33:36 +0100 From: Poul-Henning Kamp <phk@critter.freebsd.dk> To: smp@freebsd.org Subject: SMP/PIIX "calcru: negative time" Message-ID: <20993.943875216@critter.freebsd.dk>
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This patch should hopefully fix a lot of the "calcru: negative time"
warnings on SMP systems.
Intel forgot that reading an asynchronous counter needs a
latch to get reliable readings: There is about 4% risk
of reading a bogus value from the PIIX counter.
I have also added some checks to try to avoid using bogus
timestamps should they occur again/still.
Please let me know if you see either of the "calcru: negative time"
or the new ""microuptime() went backwards ..." warnings after this
change. Please include your boot dmesg and output from sysctl -a
in your email.
Poul-Henning
------- Forwarded Message
Message-Id: <199911291127.DAA37357@freefall.freebsd.org>
From: Poul-Henning Kamp <phk@FreeBSD.org>
Date: Mon, 29 Nov 1999 03:27:42 -0800 (PST)
To: cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org
Subject: cvs commit: src/sys/i386/i386 mp_clock.c
Sender: owner-cvs-committers@FreeBSD.org
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X-UIDL: c7ea5d26ec5590356755c8c7a3926448
phk 1999/11/29 03:27:42 PST
Modified files:
sys/i386/i386 mp_clock.c
Log:
How hard can it be to implement a 24bit counter in hardware ?
Make sure we read a likely value from the PIIX timecounter.
This should fix a large fraction of the "calcru: negative time"
warnings produced by SMP machines.
Another hole in one by: bde
Didn't belive Bruce: phk
Revision Changes Path
1.4 +34 -2 src/sys/i386/i386/mp_clock.c
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