Process I/O Stats

As of Version 2.4.0, collectl will now determine if process i/o stats have been built into the kernel and if so, will add 2 additional columns to the process display named RKB and WKB, noting in the following example I've set the display interval to 1 second and removed the initialization message from the output. As with all fields reported as rates/sec these will show consistent values independent of the interval and if you want the unnormalized value be sure to include that option with the -o switch as -on.

[root@opteron167 collectl]# collectl -sZ -i:1
# PROCESS SUMMARY (faults are /sec)
# PID  User     PR  PPID S   VSZ   RSS  SysT  UsrT Pct  AccuTime  RKB  WKB MajF MinF Command
    1  root     20     0 S    4M  552K  0.00  0.00   0   0:00.68    0    0    0    0 init
    2  root     15     0 S     0     0  0.00  0.00   0   0:00.00    0    0    0    0 kthreadd
    3  root     RT     2 S     0     0  0.00  0.00   0   0:00.02    0    0    0    0 migration/0

A particularly useful feature I've found is monitoring one or more processes by name (you can also monitor by pid, ppid and uid) to see what they're doing. In this case I'm using the dt program to write a large file and telling collectl to display any process whose command string matches dt as well as to include time stamps.

[root@opteron167 collectl]# collectl -sZ -i:1 -Zcdt -oT
# PROCESS SUMMARY (faults are /sec)
#          PID  User     PR  PPID S   VSZ   RSS  SysT  UsrT Pct  AccuTime  RKB  WKB MajF MinF Command
09:01:03 13577  root     20 12775 R    1M    1M  0.04  0.00   4   0:01.92    0  16K    0    0 ./dt
09:01:04 13577  root     20 12775 D    1M    1M  0.40  0.00  40   0:02.32    0 118K    0    0 ./dt
09:01:05 13577  root     20 12775 D    1M    1M  0.24  0.00  24   0:02.56    0  65K    0    0 ./dt

Finally, note that there is more process I/O data available but I chose to leave it off the default display and instead have the following alternate format. This is the same methodology used for reporting process memory utilitation, namely you only see VSZ and RSS in the default display but much more with --procopt m. Also note in this case I chose 1/2 second monitoring as well as showing time in msec resolution:

[root@opteron167 collectl]# collectl --procopts i -i:.5 -Zcdt -oTm
waiting for .5 second sample...
#              PID  User     S  SysT  UsrT   RKB   WKB  RKBC  WKBC  RSYS  WSYS  CNCL  Command
09:03:24.003 13614  root     D  0.12  0.00     0   32K     0   32K     0    64     0  ./dt
09:03:24.503 13614  root     D  0.14  0.00     0   32K     0   32K     0    64     0  ./dt
09:03:25.003 13614  root     R  0.10  0.00     0   24K     0   24K     0    48     0  ./dt

Naturally, as with all other data in collectl, you can record it to a file and play it back later also using --procopts i or m. Finally, if you're new to collectl be sure to visit the home page and learn more about it as collectl collect's a lot more than just process data. It can monitor cpu, disk, memory, network, infiniband, lustre, nfs, socket, slabs and a few other things as well.