How to debug high system load?

[Heinz Diehl]

On 12.07.2012, Suvayu Ali wrote: 

> 1. `fsync() on a file': Firefox, Google Chrome, pidgin, emacs
> 2. `Waiting for buffer IO to complete': jbd2/dm-*
[....]

Fsync is expensive, but that's the way it is.

If you're using cfq as your scheduler, try this in rc.local:

echo "32" > /sys/block/sda/queue/iosched/quantum
echo "0" > /sys/block/sda/queue/iosched/slice_idle
echo "1" > /sys/block/sda/queue/iosched/low_latency
echo "51200" > /sys/block/sda/queue/nr_requests

Together with this in /etc/sysctl.conf:

vm.dirty_ratio = 10
vm.dirty_background_ratio = 5