Message-ID: <406BB238.2050207@nortelnetworks.com>
Date: Thu, 01 Apr 2004 01:10:00 -0500
From: Chris Friesen <cfriesen@nortelnetworks.com>
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To: root@chaos.analogic.com
CC: Chuck Lever <cel@citi.umich.edu>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: timer question
References: <Pine.BSO.4.33.0403311609180.17377-100000@citi.umich.edu> <Pine.LNX.4.53.0403311628120.12948@chaos>
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Richard B. Johnson wrote:
> On Wed, 31 Mar 2004, Chuck Lever wrote:
> 
> 
>>hi all-
>>
>>i'm looking for a way to do microsecond resolution timing in the RPC
>>client.  i need a timer or timestamp function that is fairly cheap, that i
>>can call on any hardware platform, and that i can invoke from inside a
>>bottom half.
>>
>>any suggestions?

As Dick Johnson said, x86 has rdtsc.  PowerPC has the mftbr, which is 
equivalent.  MIPS has something similar.

Many architectures have something, but currently it has to be coded for 
each.

One thing that might be nice would be a common API to get a high-res 
timestamp, something like a 64-bit nano_uptime, which would be good for 
uptimes of up to 524 years at nanosecond precision.  Or else you could 
just use timespec, although its not as nice on actual 64-bit machines.

Chris

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