I/O scheduling (pdflush) on the XO

[M. Edward (Ed) Borasky]

Mikus Grinbergs wrote:
> For the fun of it, started a resource-intensive task (100% CPU, 
> sporadic floods of disk writes) on my G1G1 XO.  Eventually, it 
> failed with a "severe (38)" fortran error trying to write its 
> checkpoint file {mikus note: many quick small write operations}.

Why? This device has a 433 MHz 32-bit processor, 256 MB of RAM and a 1 
GB jffs2 flash disk. What do you expect?
> 
> That situation may be a pathological one -- but what I found 
> interesting was that in again doing something similar (different 
> worktask), 'top' showed 'pdflush' requiring lots of CPU (up to 
> 52%!!). [And 'jffs2_gcd_mtd0' keeps showing up on 'top', too.]
> 
> I take it that my XO is *struggling* when presented with heavy 
> "disk I/O".

Again, where's the surprise here? An XO is *not* a scientific 
workstation! It's a computer for elementary school students!

If you want to run stuff like this, do it on a "school server" class 
machine and write an XO client.