looking for a summary of what are different kernel threads
Hi everyone,
has anyone come upon a good summary of what different kernel threads are? aoi, events, fc_dl_1, ib_addr, ib_cm, iw_cm_wc, kblockd, khelper, kthread, local_sa, migration, kjournald, watchdog, etc. It would be handy to have them described in one document - at least the most common kernel threads.
Kernel threads are marked in the ps output with square brackets. An example of output from a RHEL5 system:
[root@coke ~]# ps aux|grep ]
root 1 0.0 0.0 10368 760 ? Ss 10:44 0:03 init [3]
root 2 0.0 0.0 0 0 ? S< 10:44 0:00 [migration/0]
root 3 0.0 0.0 0 0 ? SN 10:44 0:00 [ksoftirqd/0]
root 4 0.0 0.0 0 0 ? S< 10:44 0:00 [watchdog/0]
root 5 0.0 0.0 0 0 ? S< 10:44 0:00 [migration/1]
root 6 0.0 0.0 0 0 ? SN 10:44 0:00 [ksoftirqd/1]
root 7 0.0 0.0 0 0 ? S< 10:44 0:00 [watchdog/1]
root 8 0.0 0.0 0 0 ? S< 10:44 0:00 [migration/2]
root 9 0.0 0.0 0 0 ? SN 10:44 0:00 [ksoftirqd/2]
root 10 0.0 0.0 0 0 ? S< 10:44 0:00 [watchdog/2]
root 11 0.0 0.0 0 0 ? S< 10:44 0:00 [migration/3]
root 12 0.0 0.0 0 0 ? SN 10:44 0:00 [ksoftirqd/3]
root 13 0.0 0.0 0 0 ? S< 10:44 0:00 [watchdog/3]
root 14 0.0 0.0 0 0 ? S< 10:44 0:00 [migration/4]
root 15 0.0 0.0 0 0 ? SN 10:44 0:00 [ksoftirqd/4]
root 16 0.0 0.0 0 0 ? S< 10:44 0:00 [watchdog/4]
root 17 0.0 0.0 0 0 ? S< 10:44 0:00 [migration/5]
root 18 0.0 0.0 0 0 ? SN 10:44 0:00 [ksoftirqd/5]
root 19 0.0 0.0 0 0 ? S< 10:44 0:00 [watchdog/5]
root 20 0.0 0.0 0 0 ? S< 10:44 0:00 [migration/6]
root 21 0.0 0.0 0 0 ? SN 10:44 0:00 [ksoftirqd/6]
root 22 0.0 0.0 0 0 ? S< 10:44 0:00 [watchdog/6]
root 23 0.0 0.0 0 0 ? S< 10:44 0:00 [migration/7]
root 24 0.0 0.0 0 0 ? SN 10:44 0:00 [ksoftirqd/7]
root 25 0.0 0.0 0 0 ? S< 10:44 0:00 [watchdog/7]
root 26 0.0 0.0 0 0 ? S< 10:44 0:00 [migration/8]
root 27 0.0 0.0 0 0 ? SN 10:44 0:00 [ksoftirqd/8]
root 28 0.0 0.0 0 0 ? S< 10:44 0:00 [watchdog/8]
root 29 0.0 0.0 0 0 ? S< 10:44 0:00 [migration/9]
root 30 0.0 0.0 0 0 ? SN 10:44 0:00 [ksoftirqd/9]
root 31 0.0 0.0 0 0 ? S< 10:44 0:00 [watchdog/9]
root 32 0.0 0.0 0 0 ? S< 10:44 0:00 [migration/10]
root 33 0.0 0.0 0 0 ? SN 10:44 0:00 [ksoftirqd/10]
root 34 0.0 0.0 0 0 ? S< 10:44 0:00 [watchdog/10]
root 35 0.0 0.0 0 0 ? S< 10:44 0:00 [migration/11]
root 36 0.0 0.0 0 0 ? SN 10:44 0:00 [ksoftirqd/11]
root 37 0.0 0.0 0 0 ? S< 10:44 0:00 [watchdog/11]
root 38 0.0 0.0 0 0 ? S< 10:44 0:00 [events/0]
root 39 0.0 0.0 0 0 ? S< 10:44 0:00 [events/1]
root 40 0.0 0.0 0 0 ? S< 10:44 0:00 [events/2]
root 41 0.0 0.0 0 0 ? S< 10:44 0:00 [events/3]
root 42 0.0 0.0 0 0 ? S< 10:44 0:00 [events/4]
root 43 0.0 0.0 0 0 ? S< 10:44 0:00 [events/5]
root 44 0.0 0.0 0 0 ? S< 10:44 0:00 [events/6]
root 45 0.0 0.0 0 0 ? S< 10:44 0:00 [events/7]
root 46 0.0 0.0 0 0 ? S< 10:44 0:00 [events/8]
root 47 0.0 0.0 0 0 ? S< 10:44 0:00 [events/9]
root 48 0.0 0.0 0 0 ? S< 10:44 0:00 [events/10]
root 49 0.0 0.0 0 0 ? S< 10:44 0:00 [events/11]
root 50 0.0 0.0 0 0 ? S< 10:44 0:00 [khelper]
root 313 0.0 0.0 0 0 ? S< 10:44 0:00 [kthread]
root 329 0.0 0.0 0 0 ? S< 10:44 0:00 [kblockd/0]
root 330 0.0 0.0 0 0 ? S< 10:44 0:00 [kblockd/1]
root 331 0.0 0.0 0 0 ? S< 10:44 0:00 [kblockd/2]
root 332 0.0 0.0 0 0 ? S< 10:44 0:00 [kblockd/3]
root 333 0.0 0.0 0 0 ? S< 10:44 0:00 [kblockd/4]
root 334 0.0 0.0 0 0 ? S< 10:44 0:00 [kblockd/5]
root 335 0.0 0.0 0 0 ? S< 10:44 0:00 [kblockd/6]
root 336 0.0 0.0 0 0 ? S< 10:44 0:00 [kblockd/7]
root 337 0.0 0.0 0 0 ? S< 10:44 0:00 [kblockd/8]
root 338 0.0 0.0 0 0 ? S< 10:44 0:00 [kblockd/9]
root 339 0.0 0.0 0 0 ? S< 10:44 0:00 [kblockd/10]
root 340 0.0 0.0 0 0 ? S< 10:44 0:00 [kblockd/11]
root 341 0.0 0.0 0 0 ? S< 10:44 0:00 [kacpid]
root 509 0.0 0.0 0 0 ? S< 10:44 0:00 [cqueue/0]
root 510 0.0 0.0 0 0 ? S< 10:44 0:00 [cqueue/1]
root 511 0.0 0.0 0 0 ? S< 10:44 0:00 [cqueue/2]
root 512 0.0 0.0 0 0 ? S< 10:44 0:00 [cqueue/3]
root 513 0.0 0.0 0 0 ? S< 10:44 0:00 [cqueue/4]
root 514 0.0 0.0 0 0 ? S< 10:44 0:00 [cqueue/5]
root 515 0.0 0.0 0 0 ? S< 10:44 0:00 [cqueue/6]
root 516 0.0 0.0 0 0 ? S< 10:44 0:00 [cqueue/7]
root 517 0.0 0.0 0 0 ? S< 10:44 0:00 [cqueue/8]
root 518 0.0 0.0 0 0 ? S< 10:44 0:00 [cqueue/9]
root 519 0.0 0.0 0 0 ? S< 10:44 0:00 [cqueue/10]
root 520 0.0 0.0 0 0 ? S< 10:44 0:00 [cqueue/11]
root 523 0.0 0.0 0 0 ? S< 10:44 0:00 [khubd]
root 525 0.0 0.0 0 0 ? S< 10:44 0:00 [kseriod]
root 684 0.0 0.0 0 0 ? S 10:44 0:00 [khungtaskd]
root 685 0.0 0.0 0 0 ? S 10:44 0:00 [pdflush]
root 686 0.2 0.0 0 0 ? S 10:44 0:14 [pdflush]
root 687 0.0 0.0 0 0 ? S< 10:44 0:00 [kswapd0]
root 688 0.0 0.0 0 0 ? S< 10:44 0:00 [kswapd1]
root 689 0.0 0.0 0 0 ? S< 10:44 0:00 [aio/0]
root 690 0.0 0.0 0 0 ? S< 10:44 0:00 [aio/1]
root 691 0.0 0.0 0 0 ? S< 10:44 0:00 [aio/2]
root 692 0.0 0.0 0 0 ? S< 10:44 0:00 [aio/3]
root 693 0.0 0.0 0 0 ? S< 10:44 0:00 [aio/4]
root 694 0.0 0.0 0 0 ? S< 10:44 0:00 [aio/5]
root 695 0.0 0.0 0 0 ? S< 10:44 0:00 [aio/6]
root 696 0.0 0.0 0 0 ? S< 10:44 0:00 [aio/7]
root 697 0.0 0.0 0 0 ? S< 10:44 0:00 [aio/8]
root 698 0.0 0.0 0 0 ? S< 10:44 0:00 [aio/9]
root 699 0.0 0.0 0 0 ? S< 10:44 0:00 [aio/10]
root 700 0.0 0.0 0 0 ? S< 10:44 0:00 [aio/11]
root 855 0.0 0.0 0 0 ? S< 10:44 0:00 [kpsmoused]
root 990 0.0 0.0 0 0 ? S< 10:44 0:00 [scsi_eh_0]
root 991 0.0 0.0 0 0 ? S< 10:44 0:00 [qla2xxx_0_dpc]
root 992 0.0 0.0 0 0 ? S< 10:44 0:00 [scsi_wq_0]
root 993 0.0 0.0 0 0 ? S< 10:44 0:00 [fc_wq_0]
root 994 0.0 0.0 0 0 ? S< 10:44 0:00 [fc_dl_0]
root 995 0.0 0.0 0 0 ? S< 10:44 0:00 [scsi_eh_1]
root 996 0.0 0.0 0 0 ? S< 10:44 0:00 [qla2xxx_1_dpc]
root 997 0.0 0.0 0 0 ? S< 10:44 0:00 [scsi_wq_1]
root 998 0.0 0.0 0 0 ? S< 10:44 0:00 [fc_wq_1]
root 999 0.0 0.0 0 0 ? S< 10:44 0:00 [fc_dl_1]
root 1026 0.0 0.0 0 0 ? S< 10:44 0:00 [kstriped]
root 1079 0.0 0.0 0 0 ? S< 10:44 0:00 [ksnapd]
root 1134 0.0 0.0 0 0 ? S< 10:44 0:05 [kjournald]
root 1159 0.0 0.0 0 0 ? S< 10:44 0:00 [kauditd]
root 1995 0.0 0.0 0 0 ? S< 10:44 0:00 [kedac]
root 2826 0.0 0.0 0 0 ? S< 10:44 0:00 [kmpathd/0]
root 2827 0.0 0.0 0 0 ? S< 10:44 0:00 [kmpathd/1]
root 2828 0.0 0.0 0 0 ? S< 10:44 0:00 [kmpathd/2]
root 2829 0.0 0.0 0 0 ? S< 10:44 0:00 [kmpathd/3]
root 2830 0.0 0.0 0 0 ? S< 10:44 0:00 [kmpathd/4]
root 2831 0.0 0.0 0 0 ? S< 10:44 0:00 [kmpathd/5]
root 2832 0.0 0.0 0 0 ? S< 10:44 0:00 [kmpathd/6]
root 2833 0.0 0.0 0 0 ? S< 10:44 0:00 [kmpathd/7]
root 2834 0.0 0.0 0 0 ? S< 10:44 0:00 [kmpathd/8]
root 2835 0.0 0.0 0 0 ? S< 10:44 0:00 [kmpathd/9]
root 2836 0.0 0.0 0 0 ? S< 10:44 0:00 [kmpathd/10]
root 2837 0.0 0.0 0 0 ? S< 10:44 0:00 [kmpathd/11]
root 2838 0.0 0.0 0 0 ? S< 10:44 0:00 [kmpath_handlerd]
root 2916 0.3 0.0 0 0 ? S< 10:44 0:20 [kjournald]
root 2919 0.0 0.0 0 0 ? S< 10:44 0:00 [kjournald]
root 3044 0.0 0.0 0 0 ? S< 10:44 0:00 [iscsi_eh]
root 3193 0.0 0.0 0 0 ? S< 10:45 0:00 [cnic_wq]
root 3251 0.0 0.0 0 0 ? S< 10:45 0:00 [ib_addr]
root 3296 0.0 0.0 0 0 ? S< 10:45 0:00 [ib_mcast]
root 3298 0.0 0.0 0 0 ? S< 10:45 0:00 [ib_inform]
root 3299 0.0 0.0 0 0 ? S< 10:45 0:00 [local_sa]
root 3313 0.0 0.0 0 0 ? S< 10:45 0:00 [iw_cm_wq]
root 3327 0.0 0.0 0 0 ? S< 10:45 0:00 [ib_cm/0]
root 3329 0.0 0.0 0 0 ? S< 10:45 0:00 [ib_cm/1]
root 3330 0.0 0.0 0 0 ? S< 10:45 0:00 [ib_cm/2]
root 3331 0.0 0.0 0 0 ? S< 10:45 0:00 [ib_cm/3]
root 3332 0.0 0.0 0 0 ? S< 10:45 0:00 [ib_cm/4]
root 3333 0.0 0.0 0 0 ? S< 10:45 0:00 [ib_cm/5]
root 3334 0.0 0.0 0 0 ? S< 10:45 0:00 [ib_cm/6]
root 3335 0.0 0.0 0 0 ? S< 10:45 0:00 [ib_cm/7]
root 3336 0.0 0.0 0 0 ? S< 10:45 0:00 [ib_cm/8]
root 3337 0.0 0.0 0 0 ? S< 10:45 0:00 [ib_cm/9]
root 3338 0.0 0.0 0 0 ? S< 10:45 0:00 [ib_cm/10]
root 3339 0.0 0.0 0 0 ? S< 10:45 0:00 [ib_cm/11]
root 3352 0.0 0.0 0 0 ? S< 10:45 0:00 [rdma_cm]
root 3563 0.0 0.0 0 0 ? S< 10:45 0:00 [bond0]
root 3975 0.0 0.0 0 0 ? S< 10:45 0:00 [rpciod/0]
root 3976 0.0 0.0 0 0 ? S< 10:45 0:00 [rpciod/1]
root 3977 0.0 0.0 0 0 ? S< 10:45 0:00 [rpciod/2]
root 3978 0.0 0.0 0 0 ? S< 10:45 0:00 [rpciod/3]
root 3979 0.0 0.0 0 0 ? S< 10:45 0:00 [rpciod/4]
root 3980 0.0 0.0 0 0 ? S< 10:45 0:00 [rpciod/5]
root 3981 0.0 0.0 0 0 ? S< 10:45 0:00 [rpciod/6]
root 3982 0.0 0.0 0 0 ? S< 10:45 0:00 [rpciod/7]
root 3983 0.0 0.0 0 0 ? S< 10:45 0:00 [rpciod/8]
root 3984 0.0 0.0 0 0 ? S< 10:45 0:00 [rpciod/9]
root 3985 0.0 0.0 0 0 ? S< 10:45 0:00 [rpciod/10]
root 3986 0.0 0.0 0 0 ? S< 10:45 0:00 [rpciod/11]
root 4349 0.0 0.0 110968 6620 ? Ss 11:03 0:00 sshd: guzenkovs [priv]
root 4933 0.0 0.0 0 0 ? SN 10:45 0:00 [kipmi0]
avahi 7932 0.0 0.0 21628 1312 ? Ss 10:46 0:00 avahi-daemon: running [monitor02.local]
root 8361 0.0 0.0 110376 6608 ? Ss 10:46 0:00 sshd: guzenkovs [priv]
root 9321 0.0 0.0 110376 6596 ? Ss 10:46 0:00 sshd: guzenkovs [priv]
root 9472 0.0 0.0 110376 6592 ? Ss 10:46 0:00 sshd: guzenkovs [priv]
root 10294 0.0 0.0 110376 6608 ? Ss 10:47 0:00 sshd: guzenkovs [priv]
root 19592 0.0 0.0 61204 828 pts/3 S+ 12:21 0:00 grep ]
[root@coke ~]# ps aux | grep ] | awk -F[ '{print $2}' | awk -F/ '{print $1}' |awk -F] '{print $1}'| sort| uniq
3
aio
bond0
cnic_wq
cqueue
events
fc_dl_0
fc_dl_1
fc_wq_0
fc_wq_1
ib_addr
ib_cm
ib_inform
ib_mcast
iscsi_eh
iw_cm_wq
kacpid
kauditd
kblockd
kedac
khelper
khubd
khungtaskd
kipmi0
kjournald
kmpathd
kmpath_handlerd
kpsmoused
kseriod
ksnapd
ksoftirqd
kstriped
kswapd0
kswapd1
kthread
local_sa
migration
monitor02.local
pdflush
priv
qla2xxx_0_dpc
qla2xxx_1_dpc
rdma_cm
rpciod
scsi_eh_0
scsi_eh_1
scsi_wq_0
scsi_wq_1
watchdog
Another question is on naming convention for multiple threads of the same name. In the output above I can see three different naming conventions:
1) _0, _1, ... e.g. [scsi_wq_0], [scsi_wq_1]
2) /1, /2, ... e.g. [aio/0], [aio/1]
3) 1, 2, ... e.g. [kswapd0], [kswapd1] --note that there is only one swap disk on that system.
Is there any semantic difference between them?
