Path: utzoo!attcan!uunet!sco!seanf
From: seanf@sco.COM (Sean Fagan)
Newsgroups: comp.arch
Subject: Re: Cycle Counter
Message-ID: <3151@scolex.sco.COM>
Date: 10 Aug 89 17:45:17 GMT
References: <GRUNWALD.89Aug9162836@flute.cs.uiuc.edu> <MCCALPIN.89Aug9153545@masig3.ocean.fsu.edu>
Reply-To: seanf@scolex.UUCP (Sean Fagan)
Distribution: comp
Organization: The Santa Cruz Operation, Inc.
Lines: 18

In article <MCCALPIN.89Aug9153545@masig3.ocean.fsu.edu> mccalpin@masig3.ocean.fsu.edu (John D. McCalpin) writes:
>In the above-referenced message, Dirk Grunwald asks about cycle counters:
>>I know something like this exists on the Cray X-MP; do other machines
>>have cycle counters as well?
>Not that it makes much difference, but the ETA-10 has several extra
>registers to keep track of cycle counts for the vector and scalar units
>separately.

I've been told that the Elxsi has a clock register available, with 25ns
resolution.  Since the cycle time is 25 ns, this makes it possible to time
any instruction (mov <clock>, r1; instruction; sub <clock>, r1; or whatever
the syntax would be).  Since it's also 64 bits, I believe its epoch is
something like 14000 years from now...

-- 
Sean Eric Fagan  |    "Uhm, excuse me..."
seanf@sco.UUCP   |      -- James T. Kirk (William Shatner), ST V: TFF
(408) 458-1422   | Any opinions expressed are my own, not my employers'.