On 30 August 2014 15:08, Chris Samuel <chris@csamuel.org> wrote:

I'd suggest iotop (should be packaged) and iosnoop which is a shell script
that uses the Linux ftrace functionality to track what's going on, see here:

http://www.brendangregg.com/blog/2014-07-16/iosnoop-for-linux.html

Thanks for this. Both seem like good tools.

Only problem is, my computer seems fine right now.

Hmmm.

Another thought: really need to make sure cron isn't doing anything at the time. It doesn't show up on top, but need to double check this. Hmm. Looks like I do have anacron installed, so cron jobs do run when I turn the computer on. According to my log files, all cron jobs should have terminated when I saw the high iowait time this morning, and didn't run for long in any case. Unless something is forking and continues to run after cron reports it finished.

Will need to check this again tomorrow.

Oh, and latencytop and perf top might give insights too.

Apparently latencytop doesn't like the default Debian kernel:

falidae# latencytop

mount: none already mounted or /sys/kernel/debug/ busy

mount: according to mtab, debugfs is already mounted on /sys/kernel/debug

Please enable the CONFIG_LATENCYTOP configuration in your kernel.

Exiting...

falidae# mount -t

falidae# ls -l /sys/kernel/debug

total 0

drwxr-xr-x 2 root root 0 Aug 31 2014 acpi

drwxr-xr-x 23 root root 0 Aug 31 2014 bdi

drwxr-xr-x 2 root root 0 Aug 31 2014 dma_buf

drwxr-xr-x 4 root root 0 Aug 30 16:46 dri

drwxr-xr-x 2 root root 0 Aug 30 16:46 eeepc-wmi

drwxr-xr-x 2 root root 0 Aug 31 2014 extfrag

-r--r--r-- 1 root root 0 Aug 31 2014 gpio

drwxr-xr-x 5 root root 0 Aug 30 16:46 hid

drwxr-xr-x 2 root root 0 Aug 31 2014 kprobes

drwxr-xr-x 2 root root 0 Aug 30 16:46 kvm

drwxr-xr-x 2 root root 0 Aug 31 2014 mce

drwxr-xr-x 2 root root 0 Aug 30 16:46 mei

drwxr-xr-x 2 root root 0 Aug 30 16:46 pkg_temp_thermal

drwxr-xr-x 2 root root 0 Aug 31 2014 pstate_snb

drwxr-xr-x 2 root root 0 Aug 31 2014 regmap

-rw-r--r-- 1 root root 0 Aug 31 2014 sched_features

-r--r--r-- 1 root root 0 Aug 31 2014 sleep_time

-r--r--r-- 1 root root 0 Aug 31 2014 suspend_stats

drwxr-xr-x 6 root root 0 Aug 31 2014 tracing

drwxr-xr-x 2 root root 0 Aug 30 16:46 usb

-r--r--r-- 1 root root 0 Aug 31 2014 wakeup_sources

drwxr-xr-x 2 root root 0 Aug 31 2014 x86

--
Brian May <brian@microcomaustralia.com.au>