Path: utzoo!attcan!uunet!philmtl!philabs!ttidca!quad1!srhqla!csun!mx!cbcscmrs
From: mx!cbcscmrs@csun.edu
Newsgroups: comp.arch
Subject: Re: Cycle Counter
Message-ID: <2272@csun.edu>
Date: 18 Aug 89 02:41:36 GMT
References:  <121192@sun.Eng.Sun.COM>
Sender: news@csun.edu
Reply-To: cbcscmrs@ma.csun.edu (Mike Stump)
Distribution: comp
Organization: CSU, Northridge School of Engineering & Computer Science
Lines: 26

In article <121192@sun.Eng.Sun.COM> ram@sun.UUCP (Renu Raman) writes:
>In article  grunwald@flute.cs.uiuc.edu writes:
>>When doing performance monitoring, benchmarking or profiling, you want
>>a high-resolution timer. Some systems have microsecond timers, and
>>those are considered pretty snazzy; I know I was overjoyed when I
>>found one on the Encore. Normal machines, e.g., a Sun, have about 5
>>millisecond resolution. That's pathetic.
>
>   Depends on what kind of a "normal" Sun you have.  Anything since
>   SPARCstation should have a micro-second timer (only 21 bits tho') - so
>   2 second is all you have if you want to watch anything.

I like nanosecond timers, built into the instruction set!
You can tell how far the head on the disk moved if you hit a page
fault!

The elxsi has a 25 nanosecond resolution process timer (to measure CPU time)
and a CPU wide real time clock that also has 25 nanosecond resolution.

Oh, unlike the 21 bits SPARCstation timer, on the elxsi you have to wait
a little longer if you want to see the counter overflow.  About 7,311
years and 284 days.  Yes, that is 63 bits. :-)  I think they are signed,
and no, I don't know why...  (Does it really matter at that point?)

Syncing the thing up to a chimmer takes on a new meaning... :-)
(NTP time servers...)