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.
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.
Marco Pesenti Gritti wrote:
Hi,
with the latest kernel strace is working on the board, so I've been
able to track down the issue with the very very slow pygtk startup.
For people not following the sugar list:
http://mailman.laptop.org/pipermail/sugar/2006-August/000244.html
A simple pygtk app is opening around 700 files on startup, a lot of
these being ENOENT, and stat-ing another 200. A large part of the
startup time seem to be due to this.
So I did some profiling of the 'open' performance, using the attached
test case. I bet there is a better way, but I think the results are
interesting. The test case opens 10000 files, the results are the
following:
OLPC + USB hard disk : 6.5 seconds
My laptop: 0.73 seconds
My laptop + USB hard disk: 0.75 seconds
OLPC is 9 times slower.
My question is... can we expect this to be solved (or at least
drastically reduced) in hardware or kernel space?
Thanks,
Marco
------------------------------------------------------------------------
import sys
import time
import random
t = time.time()
i = 0
while i < 10000:
try:
f = open('/media/OLPCRoot/bubu%d' % random.random(), 'r')
f.close()
except:
pass
i += 1
new_t = time.time()
print '10000 open: %f' % (new_t - t)
t = new_t
------------------------------------------------------------------------
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