Na stronie iostat
podręcznej znalazłem dwie podobne kolumny:
await
The average time (in milliseconds) for I/O requests issued to the device to be served. This
includes the time spent by the requests in queue and the time spent servicing them.
svctm
The average service time (in milliseconds) for I/O requests that were issued to the device.
Warning! Do not trust this field any more. This field will be removed in a future sysstat
version.
Czy te kolumny mają reprezentować to samo? Wydaje mi się, że czasami się zgadzają, ale czasem nie:
avg-cpu: %user %nice %system %iowait %steal %idle
4.44 0.02 1.00 0.36 0.00 94.19
Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util
sda 0.07 0.96 0.28 1.28 8.98 47.45 72.13 0.02 11.36 11.49 11.34 5.71 0.89
avg-cpu: %user %nice %system %iowait %steal %idle
8.00 0.00 2.50 2.50 0.00 87.00
Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util
sda 0.00 9.00 2.00 6.00 12.00 68.00 20.00 0.05 6.00 2.00 7.33 6.00 4.80
avg-cpu: %user %nice %system %iowait %steal %idle
4.57 0.00 0.51 0.00 0.00 94.92
Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util
sda 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
avg-cpu: %user %nice %system %iowait %steal %idle
13.93 0.00 1.99 1.49 0.00 82.59
Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util
sda 0.00 29.00 0.00 4.00 0.00 132.00 66.00 0.03 7.00 0.00 7.00 7.00 2.80
Oprócz oczywistego ostrzeżenia, które svctm
jest amortyzowane, jaka jest różnica między tymi dwiema kolumnami ?
źródło
await
=svctm
+however_long_in_queue
, tak jak stwierdza to drobna instrukcja!