SYSRUTH@utorphys.bitnet (Ruth Milner) (01/21/89)
In v7n101, Robert Wenig (acad!robert@uunet.uu.net) asks:
>How do I detect whether or not a 4/110 actually has the FPU installed?
The Sun 4 (all models) FPU is not an option, but an integral part of the
CPU that does all floating-point operations. Sun 4's do not even support
-fsoft, because the FPU is always there. If it dies, not even your kernel
will run. Note that the man pages for cc and f77 mention this, and also
that there is no place in the config. file to put an entry for one.
If you're asking because you think your 4/110 is kind of slow for a Sun 4,
well, that's probably just the normal speed for a Sun 4/110 :-). Unless
there's something wrong with it, of course. It should be about .6-.7 of a
Sun 4/2x0.
Ruth Milner
Systems Manager
University of Toronto Physics
sysruth@helios.physics.utoronto.cahedrick@geneva.rutgers.edu (Charles Hedrick) (01/28/89)
>The Sun 4 (all models) FPU is not an option, but an integral part of the >CPU that does all floating-point operations. ?? Take a look at your Sun catalog. The 4/110S-8 and 4/110SE-8 differ only in that the SE has an FPU and the S does not. It's true that there is no -fsoft. This is because the kernel traps floating point instructions on machines without the FPU. It emulates the FPU.
ekrell@ulysses.att.com (01/28/89)
>The Sun 4 (all models) FPU is not an option, but an integral part of the >CPU that does all floating-point operations. There is an FPU on the Sun 4s (the Weitek coprocessor). It's standard on the 4/200's but is optional on the 4/110 (look at Sun's price list), so the question is how do you know the 4/110 you got does indeed have an FPU? We need something like /usr/etc/mc68881version on the Sun 3's. -- Eduardo Krell AT&T Bell Laboratories, Murray Hill, NJ UUCP: {att,decvax,ucbvax}!ulysses!ekrell Internet: ekrell@ulysses.att.com
barry@ames.arc.nasa.gov (Barry Lustig) (01/31/89)
SYSRUTH@utorphys.bitnet (Ruth Milner) writes: > The Sun 4 (all models) FPU is not an option, but an integral part of the > CPU that does all floating-point operations. Sun 4's do not even support > -fsoft, because the FPU is always there. If it dies, not even your kernel > will run. Note that the man pages for cc and f77 mention this, and also > that there is no place in the config. file to put an entry for one. Wrong, wrong, wrong. You can buy a 4/110 *without* floating point. The floating point on a 4/110 is provided by a pair of Weitek floating point chips. The floating upgrade costs $2,650. If your machine doesn't have floating point, the kernel provides software emulation of the floating point instructions. This differs with the Sun 3s, where the floating point code is inserted, inline, into the user's binary. We did some simple benchmarks on a 4/110 with and without the floating point. The code we timed was some part of the GBRL ray tracing package. In some cases, the performance of the software floating point was as much as 200 times slower than with the hardware. Barry Lustig Advanced Decision Systems barry@ADS.COM [[ Thanks to everyone else who contributed similar information. --wnl ]]
pvo1478@oce.orst.edu (Paul V. O'Neill) (02/01/89)
>Ruth Milner (v7n114) reports all Sun 4's come with FPU's.
Sorry, this is totally wrong. FPU for a 4/110 is optional and simulation
of a missing FPU is in the kernel (which is why you don't have any -fxxx
options.)
To see if you have an FPU installed:
"time program_name"
Assuming program_name has a lot of floating point calculations, it will
run very slowly (about 20-90 times slower than a 3/50 w/ 68881) and time
will report tons of system time if you don't have an FPU. If you do have
an FPU, it will scream and system time will be ~0.0.
See sun-spots v6n217, v6n222, v6n235, v6n279
Paul O'Neill pvo@oce.orst.edu
Coastal Imaging Lab
OSU--Oceanography
Corvallis, OR 97331 503-754-3251