Message-ID: <437A2FDA.6090204@mvista.com>
Date: Tue, 15 Nov 2005 10:58:34 -0800
From: George Anzinger <george@mvista.com>
Reply-To: george@mvista.com
Organization: MontaVista Software
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To: evan@coolrunningconcepts.com
CC: linux-kernel@vger.kernel.org, john stultz <johnstul@us.ibm.com>
Subject: Re: Timer idea
References: <20051115102425.0iln2874xjoc4g84@coolrunningconcepts.com>
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evan@coolrunningconcepts.com wrote:
> I was thinking about benchmarking, profiling, and various other applications
> that might need frequent access to the current time.  Polling timers or
> frequent timer signal delivery both seem like there would be a lot of overhead.
>  I was thinking it would be nice if you could just read the time information
> without making an OS call.
> 
> I figure the kernel keeps accurate records of current time information and the
> values of various timers.  I then had the idea that one could have a /dev or
> maybe a /proc entry that would allow you to mmap() the kernel records (read
> only) and then you could read this information right from the kernel without
> any overhead.
> 

Your are describing the vsyscall.  John Stultz and company are actively working on this as we speak. 
  If memory serves, it is already available on some platforms.

-- 
George Anzinger   george@mvista.com
HRT (High-res-timers):  http://sourceforge.net/projects/high-res-timers/
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