b) completion of synchronous block I/O initiated by the task
c) swapping in pages
d) memory reclaim
+e) thrashing page cache
+f) direct compact
and makes these statistics available to userspace through
the taskstats interface.
statistics. The delay accounting functionality populates specific fields of
this structure. See
- include/linux/taskstats.h
+ include/uapi/linux/taskstats.h
for a description of the fields pertaining to delay accounting.
It will generally be in the form of counters returning the cumulative
-delay seen for cpu, sync block I/O, swapin, memory reclaim etc.
+delay seen for cpu, sync block I/O, swapin, memory reclaim, thrash page
+cache, direct compact etc.
Taking the difference of two successive readings of a given
counter (say cpu_delay_total) for a task will give the delay
General format of the getdelays command::
- getdelays [-t tgid] [-p pid] [-c cmd...]
-
+ getdelays [-dilv] [-t tgid] [-p pid]
Get delays, since system boot, for pid 10::
- # ./getdelays -p 10
+ # ./getdelays -d -p 10
(output similar to next case)
Get sum of delays, since system boot, for all pids with tgid 5::
- # ./getdelays -t 5
-
-
- CPU count real total virtual total delay total
- 7876 92005750 100000000 24001500
- IO count delay total
- 0 0
- SWAP count delay total
- 0 0
- RECLAIM count delay total
- 0 0
+ # ./getdelays -d -t 5
+ print delayacct stats ON
+ TGID 5
-Get delays seen in executing a given simple command::
- # ./getdelays -c ls /
+ CPU count real total virtual total delay total delay average
+ 8 7000000 6872122 3382277 0.423ms
+ IO count delay total delay average
+ 0 0 0ms
+ SWAP count delay total delay average
+ 0 0 0ms
+ RECLAIM count delay total delay average
+ 0 0 0ms
+ THRASHING count delay total delay average
+ 0 0 0ms
+ COMPACT count delay total delay average
+ 0 0 0ms
- bin data1 data3 data5 dev home media opt root srv sys usr
- boot data2 data4 data6 etc lib mnt proc sbin subdomain tmp var
+Get IO accounting for pid 1, it works only with -p::
+ # ./getdelays -i -p 1
+ printing IO accounting
+ linuxrc: read=65536, write=0, cancelled_write=0
- CPU count real total virtual total delay total
- 6 4000250 4000000 0
- IO count delay total
- 0 0
- SWAP count delay total
- 0 0
- RECLAIM count delay total
- 0 0
+The above command can be used with -v to get more debug information.