I was running some simulations on LTspice and it is not even using 5% of my CPU. Nothing else is topping it and the entire computer is pretty much at idle. What could be limiting the speed?
One of the main reasons I bought a laptop with an i7 processor was to speed simulations. Is this wasted on LTspice or am I doing something wrong?
-- Rick C
I think it saves the waveforms to a file as it goes along simulating. Where you the one who complained about your hdd being slow in an earlier thread? maybe try running the sim from an ext usb stick. if that helps it's definitely the hdd.
It might be worth buying more RAM or a solid state hard disk.
LTSpice can get very slow when the waveform files are are being swapped out of RAM onto hard disk.
-- Bill Sloman, Sydney
I'd start with a ramdisk and see then. USB sticks are glacial compared with real flash drives.
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
Make sure the hard drives are running in DMA mode not PIO mode.
They automatically and permanently fall back to PIO mode if there are hardware errors.
mark
Isn't there a way to save fewer nodes?
-- John Larkin Highland Technology, Inc lunatic fringe electronics
NONE of the computer features I can see in Task Manager are being taxed at all. The disk is near zero utilization and there are 2 GB of free memory. I just watched and LTspice was only using 5% of the CPU.
-- Rick C
Try this one. 32 seconds on my new Dell. Runs about 25% CPU.
Version 4 SHEET 1 880 680 WIRE 16 -16 -160 -16 WIRE 208 -16 16 -16 WIRE 336 -16 208 -16 WIRE 208 48 208 -16 WIRE 336 48 336 -16 WIRE -160 144 -160 -16 WIRE 16 144 16 -16 WIRE 208 192 208 128 WIRE 336 192 336 112 WIRE 336 192 208 192 WIRE 208 256 208 192 WIRE 16 304 16 224 WIRE 144 304 16 304 WIRE -160 352 -160 224 WIRE 16 400 16 304 WIRE 208 400 208 352 WIRE 16 544 16 464 WIRE 208 544 208 480 FLAG 208 544 0 FLAG 16 544 0 FLAG -160 352 0 SYMBOL ind2 192 32 R0 WINDOW 0 -50 31 Left 2 WINDOW 3 -54 69 Left 2 SYMATTR InstName L1 SYMATTR Value 1m SYMATTR Type ind SYMBOL ind2 224 496 R180 WINDOW 0 -54 75 Left 2 WINDOW 3 -63 38 Left 2 SYMATTR InstName L2
SYMATTR Type ind SYMBOL cap 320 48 R0 WINDOW 0 63 12 Left 2 WINDOW 3 59 51 Left 2 SYMATTR InstName C1 SYMATTR Value 50n SYMBOL cap 0 400 R0 WINDOW 0 61 10 Left 2 WINDOW 3 64 46 Left 2 SYMATTR InstName C2
SYMBOL npn 144 256 R0 WINDOW 0 116 42 Left 2 WINDOW 3 92 77 Left 2 SYMATTR InstName Q1 SYMATTR Value BC847B SYMBOL res 0 128 R0 WINDOW 0 52 39 Left 2 WINDOW 3 49 75 Left 2 SYMATTR InstName R1 SYMATTR Value 20K SYMBOL voltage -160 128 R0 WINDOW 0 51 41 Left 2 WINDOW 3 50 75 Left 2 SYMATTR InstName V1 SYMATTR Value 10 TEXT 240 232 Left 2 !K L1 L2 0.98 TEXT -240 480 Left 2 !.tran 0 20m 0 10n uic TEXT 424 272 Left 2 ;LC Oscillator from C5A TEXT 416 312 Left 2 ;Boresight Alignment Kit TEXT 448 376 Left 2 ;JL roughly 1975
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Yes. True for any spice. Once it starts memory swapping, its all over. Always get as much memory as you can if running spice.
I've had 16 GB on my computers for many years now.
-- Kevin Aylward
Mine is an i7 and runs about 25% (only one core, apparently) and takes about 53 seconds. The computer is about 5 years old.
64bit ltspice under wine in ubuntu on ancient i7-965 20 seconds using 12% (1 core out of 8)
It's going to be over a minute and the CPU usage never got above 20% total with spice taking less than 5%. Disk activity was minimal, under
450 kB/s at the peaks, under 50% utilization peak.I don't see anything limiting the computer in any way. LTspice just isn't running as much as it could. Is there a setting somewhere to keep it running in the background?
-- Rick C
16 GB is pretty much standard for non-entry level now. I'm looking for a new machine to replace this piece of crap and it will have 32 GB.
There seems to be a new thing now, gaming laptops. It's hard to find a high end laptop unless it is a "gaming" machine with fancy case, colors and even RGB lighted keyboards. What crap! I just want a machine I can type on without activating the touchpad and a touchpad with *real* buttons so I can use it with my thumb on the buttons. I have to use a wireless mouse... which should have the dongle built into the damn laptop!!!
Oh, and while I'm ranting, the function keys should be FUNCTION KEYS!!! I did finally find a setting to switch the default behavior of my function keys to be function keys and the laptop specific functions are now activated by the laptop specific feature enable key... but I still can't use F4 in any apps. Seems someone, somewhere it overriding F4 being a general purpose key and feels I need yet another way to close a program. Instead of cycling the addressing mode in spreadsheets, it asks if I want to save my work before closing.
-- Rick C
I get a simulation speed average of about 150uS/sec on my i7-5500U 2.4 Ghz laptop/SSD drive combo with the "normal" solver, running on Wine/Xubuntu.
CPU usage 100%, altering the number of cores seems to make no difference. Only 6G of RAM and a rather sad 32k/256k of L1/L2 cache per core, so not really surprising it's TLB-missing all day.
Having a CPU with a nice fat L1/L2 cache probably helps a lot too - my guess is if that whatever set of matrix data structures LTSpice uses internally to represent a single stepping iteration's results can't fit inside the CPU cache you're kind of f***ed, have to head out to RAM/disk every time.
I found this in my travels.
Alternately, if you are only interested in a few node voltages and device currents, you can restrict the quantity of saved data by using the .save directive to save only those specific node voltages and device currents. In the directive, add the ?dialogbox? option to display all available nodes and currents so you can choose to save additional data of interest.
.save V(out) I(L1) V(in) dialogbox
-- Rick C
Are you using Windows Task Manager/Resource mointor on Win8/8.1/10 to look at the CPU usage?
Because it's often full of shit. ;-) Try a program like RealTemp...
I'm seeing 720 us/s, Win7, newish Dell desktop with 8G ram.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Put LTspice to a test, load a device-level circuit, select Solver=Alternate and the proper tight solution limits and watch it crawl, or more likely... hang. ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| STV, Queen Creek, AZ 85142 Skype: skypeanalog | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
Thinking outside the box... producing elegant solutions.
I doubt it. The slow warthogs are typically buried in the OS/GUI code somewhere. Can you turn off the marching waveforms? maybe it's a GUI thing?
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.