From: Albert Cahalan <albert@users.sf.net>
To: Nick Piggin <piggin@cyberone.com.au>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
"viro@parcelfarce.linux.theplanet.co.uk"
<viro@parcelfarce.linux.theplanet.co.uk>,
Albert Cahalan <albert@users.sourceforge.net>,
Andi Kleen <ak@suse.de>, Badari Pulavarty <pbadari@us.ibm.com>,
Dominik Brodowski <linux@brodo.de>,
"David S. Miller" <davem@redhat.com>,
Dipankar Sarma <dipankar@in.ibm.com>,
Christoph Hellwig <hch@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
James Bottomley <James.Bottomley@SteelEye.com>,
Jens Axboe <axboe@suse.de>, Lars Marowsky-Bree <lmb@suse.de>,
Mike Anderson <andmike@us.ibm.com>,
Patrick Mansfield <patmans@us.ibm.com>,
Russell King <rmk@arm.linux.org.uk>,
Rusty Russell <rusty@rustcorp.com.au>,
Trond Myklebust <trond.myklebust@fys.uio.no>,
Andrew Morton OSDL <akpm@osdl.org>
Subject: Re: [RFC] must fix lists
Date: 23 Oct 2003 21:06:57 -0400 [thread overview]
Message-ID: <1066957616.1623.34.camel@cube> (raw)
In-Reply-To: <3F986859.2000101@cyberone.com.au>
On Thu, 2003-10-23 at 19:46, Nick Piggin wrote:
> +o alan, Albert Cahalan: 1000 HZ timer increases the need for a stable time
> + source. Many laptops, SMI can lose ticks. ACPI timers? TSC?
Oh, I have an example for you.
Consider the Intel Plumas chipset. There are
some predictable time windows during which the
RTC will return garbage. The BIOS "fix" leads to
SMI/SMM stuff stealing large chunks of CPU time.
On a logic analyser, somebody at work observed
chunks of time as large as 4 ms. That's 3 to 5
clock ticks. Maybe that isn't worst-case even.
To avoid this disaster, Linux must _never_ touch
the RTC registers. The HPET can be used instead.
The TSC is of course also reliable, but Linux
stops using it as soon as a problem hits!
The ignore-the-TSC code really should be doing
just the opposite. Ticks are likely to be lost.
I've never seen an unstable TSC. :-)
> o 64-bit dev_t. Seems almost ready, but it's not really known how much
> work is still to do. Patches exist in -mm but with the recent rise of the
> neo-viro I'm not sure where things are at.
Hey, 32-bit dev_t is in already. That's it. Done.
next prev parent reply other threads:[~2003-10-24 1:22 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-10-21 5:46 [RFC] must fix lists Nick Piggin
2003-10-21 9:36 ` Lars Marowsky-Bree
2003-10-22 0:40 ` Nick Piggin
2003-10-21 16:18 ` Randy.Dunlap
2003-10-22 2:50 ` Albert Cahalan
2003-10-23 21:11 ` Alan Cox
2003-10-23 21:09 ` Alan Cox
2003-10-23 23:46 ` Nick Piggin
2003-10-24 1:06 ` Albert Cahalan [this message]
2003-10-24 1:55 ` viro
2003-10-24 0:23 ` Chris Wright
2003-10-25 20:18 ` Alan Cox
2003-10-27 12:53 ` [RFC][PATCH] " Nick Piggin
2003-10-27 18:24 ` ACPI PM-Timer [Was: Re: [RFC][PATCH] must fix lists] Dominik Brodowski
2003-10-27 18:42 ` john stultz
2003-10-27 18:49 ` Dominik Brodowski
2003-10-27 19:07 ` john stultz
2003-10-27 23:01 ` ACPI PM-Timer rev.2 [Was: Re: ACPI PM-Timer [Was: Re: [RFC][PATCH] must fix lists]] Dominik Brodowski
2003-11-04 22:03 ` john stultz
2003-10-27 9:48 [RFC] must fix lists Mikael Pettersson
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