XO-1 vs Sugar 0.104 performance, and swap to NAND Flash

James Cameron quozl at laptop.org
Wed Apr 1 23:54:59 EDT 2015

With Sugar 0.98 in 13.2.1, the XO-1 was so short of memory that adding
swap gave an obvious benefit.  Thanks to those who have verified this
for us.

With Sugar 0.104 in 13.2.4, things seem much better on the XO-1,
thanks to all the work done by Sugar Labs developers.  But I'm not
finished testing [1].

Meanwhile, there's an opportunity to add swap to jffs2 filesystem.

The XO-1 NAND Flash is rated for 100,000 writes per cell.  The jffs2
filesystem we use spreads the writes across all the cells.

There's a risk that swapping to the NAND Flash will shorten the life
of an XO-1.  It may become slower at reading and writing journal
entries.  But they might already be so slow that this isn't a problem
any more.

What I need is some data from XO-1 that have been used a lot: how long
does it take to reflash?  To test, surround a copy-nand command with
timing markers, like this:

ok t-sec( copy-nand u:\32014o0.img )t-sec

The result will be on the line above the ok prompt when it is done,
e.g. 403S, which is 403 seconds.  Send me the serial number, file
name, and time in seconds.


1.  free memory with no activities running is up around the 40 MB
mark.  Browse running leaves 16 MB free.  Activity startup time is
much reduced, and reduced still further when the pulsing icon
animation is switched from 10 times a second to twice a second.  The
animation is stealing resources!  On the other hand, the spinning
cursor during startup or in Browse consumes no significant resources.

http://dev.laptop.org/~quozl/z/1YdW4T.txt shows the change.

James Cameron

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