[sugar] Re: [OLPC-devel] pygtk performance issue

[Jim Gettys]

On Wed, 2006-09-06 at 14:31 +0200, Marco Pesenti Gritti wrote:
> Mitch Bradley wrote:
> > The processor on OLPC is inherently slower than the processors that 
> > are used in modern laptops.  To get ultra low power you have to 
> > sacrifice something.  It seems unlikely that we would be able to hide 
> > that inherent speed differential by a kernel change.  In the short 
> > term, I don't know of any planned hardware changes that would 
> > substantially increase the performance of file system activity on USB 
> > drives.
> >
> 
> Ok, this is the kind of feedback I was looking for. What about the 
> internal flash? Is it going to be substantially faster than USB drives?

With Cafe', performance should be pretty fast, of order the same speed
as disk on laptops for bulk data transfer, and much faster than disk for
any seeks.  It's faster than the typical USB flash device by quite a
bit.

IIRC, the flash chip is capable of 25MB/second; we should get most of
that performance with Cafe'.

> 
> > I believe that "work smarter" is a key component of the OLPC plan.  It 
> > looks like you have found some "low-hanging fruit" that is ripe for 
> > the picking.  Improving pygtk to start up in a less "brute force" way 
> > would benefit not only OLPC, but everybody else as well.
> 
> Definitely. But it's also important to prioritize the work. The whole 
> point of this mail is to figure out how critical the "opening a bunch of 
> files" issues is going to be on the final hardware/kernel.
> 

We should be CPU bound for opening files; you can simulate this on a
disk drive by ensuring you have plenty of memory and a warm buffer
cache.
                                Regards,
                                      - Jim


-- 
Jim Gettys
One Laptop Per Child