Re: which commercial HDL-Simulator for FPGA?

On Fri, 20 Jun 2008 10:52:13 -0500
General Schvantzkopf <schvantzkopf@[EMAIL PROTECTED]
> wrote:

> The NFS mounted host directory performance on VMware was 
> about the same as native XP performance which leads me to believe
> that XP's problem is it's file system.

That's hardly a convincing proof that all the performance increase is
due to file system. In my experience, NFS does slow down ncsim a lot
when I turn on the waveform dumping, but without waveform dumping,
there is no noticeable performance difference after the
design elaboration.

I'm not saying filesystem isn't part of it, but for a long simulation
with no data logging, 99% of the time the simulator is not doing file
I/O. Rather, I believe the following two play a more major role in the
speed difference:

1. Context switching. Linux is very very good at this. In a workstation
environment where I/O interrupts happen hundreds of times a second,
context switching happens everytime the CPU switch to run from one
process to the next one. What's good about the Linux kernel is that you
can tune a lot of things: the amount of interrupts, how frequently
the kernel service them, and how pre-emptible the kernel is. A
fine-tuned batch server can very fast. Not so much help from XP. I
believe Windows 2000 does have an option to choose between server and
desktop mode, but not sure what difference it makes.

2. Memory management. Linux is again very very good at this. Filesystem
caching and virtual memory management works hand-in-hand. My 1GB RAM
workstation ran 99.9% of time without going to swap partition, whereas
in Windows XP, the same workstation constantly sees harddrive
thra****ng, especially after running a very memory intensive job.



-- 
Faster, faster, you fool, you fool!
		-- Bill Cosby