What I/O activity does iostat include?

edmazur · 09-14-2009, 09:01 PM

Regarding iostat's input/output device monitoring, does this include reads/writes to sockets? I am assuming the answer is no, but would just like to verify.

I'd also like to know whether the %iowait value is affected by sockets. Meaning, if the CPU is idle and waiting on data that is being read from a socket, would this contribute to %iowait?

Quote:

%iowait - Show the percentage of time that the CPU or CPUs were idle during which the system had an outstanding disk I/O request.

unSpawn · 10-11-2009, 05:04 PM

As far as I know anything io.* tools display has to do with disk I/O.

Sockets waiting for data remain in the WAIT state you can check with say:

Code:

for s in SYN_RECV SYN_SENT CLOSING CONNECTED ESTABLISHED FIN_WAIT1 FIN_WAIT2 LAST_ACK TIME_WAIT \
UNREPLIED ASSURED; do echo "$(grep -c "$s" /proc/net/ip_conntrack) ${s}"; done | sort -bgr

and cache consumption with say:

Code:

awk '{printf "%5d KB %s\n", $3*$4/(1024), $1}' < /proc/slabinfo | sort -nr

or 'slabtop'.