From owner-freebsd-hackers@FreeBSD.ORG  Mon Mar 30 07:32:45 2009
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To: Peter Jeremy <peterjeremy@optushome.com.au>
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
In-Reply-To: Your message of "Mon, 30 Mar 2009 05:07:45 +1100."
	<20090329180745.GB38985@server.vk2pj.dyndns.org> 
Date: Mon, 30 Mar 2009 07:32:42 +0000
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Cc: Alexander Sack <pisymbol@gmail.com>,
	FreeBSD Hackers <freebsd-hackers@freebsd.org>,
	freebsd-current@freebsd.org, prashant.vaibhav@gmail.com
Subject: Re: Improving the kernel/i386 timecounter performance (GSoC
	proposal) 
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In message <20090329180745.GB38985@server.vk2pj.dyndns.org>, Peter Jeremy write
s:

>>I'm assuming folks are still in love with the TSC because it still the
>>cheapest as oppose ACPI-fast or HPET to even contemplate this?
>
>That is its major advantage.  It might be feasible to export all the
>data necessary to implement the complete CLOCK_*_FAST family.

The general attraction is that it can be read from userland by unpriviledged
programs.

On systems where the ACPI or HPET hardware can be memory-mapped, I should
be equally possible to map those read-only into userland processes.

Now _THAT_ would be interesting.

-- 
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.