[ale] Performance

[danscox at mindspring.com (Danny Cox)]

Jeff,

On Fri, 2003-11-07 at 13:44, Jeff Hubbs wrote:
> OK, I read you - but regarding the "disk IO on all the small files," is
> this mostly a read operation or a write operation?  Reason I ask, how
> would it be to leave at least the reading coming from disks on the
> individual Mosix nodes, from kernel trees set up via rsync ahead of
> time? 
> 
> When you did this, how did you establish the shared cluster file space?
> NFS?  Mosix File System (something I need to look into again - it's been
> a while)?

	Just for kicks, I made a RAM disk large enough to hold the kernel
source plus objects.  This was on a dual Athlon 1.2 GHz with 1GB ram. 
Made no difference, or perhaps I may recall a couple of seconds here or
there.  Certainly down in the grass.

	Fully 98% of the time compiling is full CPU.  The I/O is negligable in
comparison.  gcc -O2 comsumes lots of memory, but is also CPU
intensive.  The best way to speed up compiles is a faster CPU, or, as
others have suggested, many fast CPUs, either via SMP, distcc, or both.

	Now, if you do lots of "make clean; make" type work, check out ccache
(ccache.samba.org).  It's the classic time/space tradeoff.  Spiffy!

-- 
kernel, n.: A part of an operating system that preserves the
medieval traditions of sorcery and black art.

Danny