Comment 20 for bug 579117

So I decided to run latencytop here while not doing much. The wireless is on and I'm reading your e-mail. After the first refresh, here's what I see under "Global":

Scheduler: waiting for cpu 255.7ms
fsync() on a file (type 'F' for details) 29.3ms
Opening file 5.5ms

others are smaller.

Seems that's a lot of "waiting for cpu"... that was all in a process called kondemand/0

Letting it run for awhile longer...

Scheduler: waiting for cpu 289.2 ms, also from kondemand/0

Awhile longer, and it's jdb2/sda1-8 atg the top with 121.1 ms
longer still, and its firefox-bin at the top with 56.2 ms (in an fsync())
longer still and another firefox-bin with 46.9 in an fsync()
now kondemeand/0 is back at the top with 307.7ms in scheduler: waiting for cpu
now jdb2/sda1-8 at the top with 58.6, 44.1 of were in fsync()
back to firefox at 46.2 in fsync()
firefox again at 70.1 in fsync()

So just looking at the "causes", it seems that thw two biggies are

scheduler: waiting for cpu
fsync() on a file

fsync often in the 40-80 range
schedule from low tens to in the hundreds

hmm just see an ACPI hardware access at 38.6 and reading ext3 directory htree at 27.

All else seems to be below 10ms.

Does this help?