comp.lang.idl-pvwave archive - RDF feed
type: channel
description: Messages from Usenet group comp.lang.idl-pvwave, compiled by Paulo Penteado
items: Re: SMP experiences with IDL

Re: SMP experiences with IDL
type: item
description: Kirt Schaper (xxx@some.place.org) writes: > Here are some timing results from a simple benchmark program > (the program simply generated a 100x100x50 random float array > and convolved it with a 10x10x10 kernel). I know that elapsed > time is not a very precise benchmark, but the systems were all > unloaded at the time of the test, and elapsed time is what makes > a system usable or not. > > ; idl version 4.01 > ; SS10/51 (50MHz) -------------- elapsed time = 59.1 seconds > ; Dec 600 5/266 (266MHz) ------- elapsed time = 43.0 seconds > ; HP 9000 C180 (180MHz) -------- elapsed time = 19.7 seconds > ; Pentium Pro (200MHz), Linux -- elapsed time = 12.1 seconds > ; Pentium II (300MHz), Linux --- elapsed time = 9.0 seconds > ; > ; idl version 5.0 > ; SS10/51 (50MHz) -------------- elapsed time =138.6 seconds > ; Pentium Pro (200MHz), Linux -- elapsed time = 45.0 seconds > ; HP 9000 C180 (180MHz) -------- elapsed time = 33.7 seconds > ; Pentium II (300MHz), Linux --- elapsed time = 31.3 seconds > > I find several things interesting about the above experience. > > (2) RSI did something quite bad to the convolution function > from v4 to v5. I spoke to RSI about this recently. They are aware of the problem and apparently have it fixed, if the data I recently saw from an IDL 5.1 beta is any indication. The numbers are back in line with the numbers for IDL 4.0. Apparently those guys have the same problem I do. You get a bright idea in the middle of the night about a program, but it turns out to be not-so-bright when it's implemented on a client's machine. Sigh... Oh, well. At least I don't have 25,000 people looking over MY shoulder. :-) Cheers, David ----------------------------------------------------------- David Fanning, Ph.D. Fanning Software Consulting E-Mail: davidf@dfanning.com Phone: 970-221-0438 Coyote's Guide to IDL Programming: http://www.dfanning.com/
creator: davidf
date: 1998-02-25T08:00:00-00:00

Re: SMP experiences with IDL
type: item
description: In article <34F3190B.41C67EA6@some.place.org>, Kirt Schaper <xxx@some.place.org> writes: > Does anyone have first hand experience with IDL (preferably > on a Linux box) running with multiple processors? Is there > any speedup? (I'm talking about IDL v5.0 for Unix). I can only speak for 4.01, but as far as the MP capabilities are concerned, that won't make a big difference. 1) You won't benefit from having more than 1 processor, as (currently) there is no threading support. So one IDL job can only make use of one CPU. Sounds worse than it is. You can either start 2 different sessions, or you can do a computation in background and still have the 2nd CPU for other tasks. Furtermore, if you have graphic-intensive interactive work, a not too small part of processing power is needed for the display. This however is done by the X-Server which is - you guess it - a different process, and can be run on the other CPU. In Fact I have a lot of graphics-intensive programs the cause a CPU-usage of 200%: 100 for the computation and 100 for the display. 2) future versions of IDL *may* support threading, if linked against the newer c-libs that are currently under development. > Our experiences with single processor Pentium/Linux boxes > suggests that they are at least as fast, if not faster, than > much more expensive HP, Dec and Sun boxes. Aside from the > problem of being a little-endian architecture, I haven't been > able to see the down-side yet. True. Our Linux PC here (only a P133) is by far the fastest IDL Machine in the observatory. If you take some care with programming, there's no problem using the same code and data with different architectures (I have a Speckle masking program that I can stop in the middle and continue the work on a different architecture). > More grist for the Linux performance mill... 0 0 | \_/ > Here are some timing results from a simple benchmark program > (the program simply generated a 100x100x50 random float array > and convolved it with a 10x10x1…
creator: pit
date: 1998-02-25T08:00:00-00:00