Re: PC164LX running slow

[Bob McElrath <mcelrath@draal.physics.wisc.edu>]

On Mon, 4 Jan 1999, Mike wrote:

> Hi,
> 
> I just received a PC164LX Alpha machine with a 533mhz processor and 2
> Meg of onboard cache and 64 megs of system ram and it seems to be
> running a little slow.  When I compile the kernel, it takes 8-10 minutes
> which seems a lot slower then my p2-300 which I find hard to believe
> since the alpha is a much faster processor.  Is it possible that some
> cache is being turned off or some other system performance option is set
> to slow? If so, how would I go about checking this and how would I set
> it to the correct setting?
> 
> The hard drive is an older seagate 4.1 gig fast-scsi barracuda, but I
> don't see why it would be causing any speed related problems, or would
> it?

This is correct.  It takes about the same time on my similarly configured
machine.  What it comes down to is: 

1) compiles are a good disk benchmark...slow disks=slow compile 

2) Alpha is 64 bit RISC.  each instruction is 64 bits.  On Intel, each
instruction varies in length (from 8 bit up to monster ones >128bit) but you
can generally encode a given task into fewer Intel instructions (and space)
than the equivalent on alpha.  Thus, alpha binaries are bigger.  Alpha
object files are bigger.  all the intermediary object files in compiling a
kernel are bigger.  You quickly slam up against memory bandwith here.

Large Kernel compile time just reflects the fact that Intel binaries are
smaller, nothing else.

-- Bob

Bob McElrath (mcelrath@draal.physics.wisc.edu) Univ. of Wisconsin at Madison