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Demonstrations of funccount, the Linux eBPF/bcc version.
This program traces kernel functions that match a specified pattern, and when
Ctrl-C is hit prints a summary of their count while tracing. Eg, tracing all
functions that begin with "vfs_":
# ./funccount 'vfs_*'
Tracing... Ctrl-C to end.
^C
ADDR FUNC COUNT
ffffffff811efe81 vfs_create 1
ffffffff811f24a1 vfs_rename 1
ffffffff81215191 vfs_fsync_range 2
ffffffff81231df1 vfs_lock_file 30
ffffffff811e8dd1 vfs_fstatat 152
ffffffff811e8d71 vfs_fstat 154
ffffffff811e4381 vfs_write 166
ffffffff811e8c71 vfs_getattr_nosec 262
ffffffff811e8d41 vfs_getattr 262
ffffffff811e3221 vfs_open 264
ffffffff811e4251 vfs_read 470
Detaching...
The above output shows that while tracing the vfs_read() function was called 470
times, and vfs_open() 264 times, etc.
This is useful for exploring kernel code, to figure out which functions are in
use and which are not. This can narrow down an investigation to just a few
functions, whose counts are similar to the workload investigated.
Tracing all tcp functions:
# ./funccount 'tcp_*'
Tracing... Ctrl-C to end.
^C
ADDR FUNC COUNT
ffffffff816baf51 tcp_try_undo_recovery 1
ffffffff816cc431 tcp_twsk_destructor 1
ffffffff816bac51 tcp_enter_recovery 1
ffffffff816c6421 tcp_xmit_retransmit_queue 1
ffffffff816b95a1 tcp_update_scoreboard 1
ffffffff816b8921 tcp_verify_retransmit_hint 1
ffffffff816c4dd1 tcp_tsq_handler.part.31 1
ffffffff816bc721 tcp_sacktag_write_queue 1
ffffffff816b8eb1 tcp_match_skb_to_sack 1
ffffffff816cd4b1 tcp_time_wait 1
ffffffff816b8c91 tcp_mark_head_lost 1
ffffffff816b8a71 tcp_init_cwnd_reduction 1
ffffffff816b90e1 tcp_sacktag_one 1
ffffffff816ba7e1 tcp_sacktag_walk 1
ffffffff816c6321 tcp_retransmit_skb 1
ffffffff816c4ec1 tcp_tasklet_func 1
ffffffff816bed01 tcp_resume_early_retransmit 1
ffffffff816b9351 tcp_dsack_set 1
ffffffff816ca181 tcp_v4_syn_recv_sock 2
ffffffff816cd3d1 tcp_ca_openreq_child 2
ffffffff816cfa91 tcp_try_fastopen 2
ffffffff816cd221 tcp_openreq_init_rwin 2
ffffffff816c8931 tcp_v4_init_req 2
ffffffff816cc461 tcp_create_openreq_child 2
ffffffff816cb841 tcp_v4_send_synack 2
ffffffff816c8121 tcp_v4_init_sequence 2
ffffffff816c2ab1 tcp_fragment 2
ffffffff816c9421 tcp_v4_conn_request 2
ffffffff816b99e1 tcp_conn_request 2
ffffffff816c88f1 tcp_v4_route_req 2
ffffffff816c1ea1 tcp_fragment_tstamp 2
ffffffff816b9511 tcp_try_keep_open 2
ffffffff816c8221 tcp_v4_reqsk_destructor 2
ffffffff816c30e1 tcp_may_send_now 2
ffffffff816c24e1 tcp_make_synack 2
ffffffff816cc8f1 tcp_child_process 2
ffffffff816cc9d1 tcp_check_req 2
ffffffff816bbaf1 tcp_fastretrans_alert 2
ffffffff816c8071 tcp_set_keepalive 2
ffffffff816c0cd1 tcp_finish_connect 3
ffffffff816c1e11 tcp_connect_queue_skb 3
ffffffff816c9c51 tcp_v4_connect 3
ffffffff816b3911 tcp_init_sock 3
ffffffff816c9051 tcp_v4_init_sock 3
ffffffff816c5111 tcp_connect 3
ffffffff816b94e1 tcp_any_retrans_done.part.35 3
ffffffff816be881 tcp_clear_retrans 3
ffffffff816b6f21 tcp_setsockopt 4
ffffffff816cf321 tcp_update_metrics 5
ffffffff816b4ee1 tcp_done 5
ffffffff816b8831 tcp_initialize_rcv_mss 5
ffffffff816b8c01 tcp_sndbuf_expand 5
ffffffff816bb921 tcp_fin 5
ffffffff816c7151 tcp_init_xmit_timers 5
ffffffff816b8301 tcp_close 5
ffffffff816cdd91 tcp_init_congestion_control 5
ffffffff816cf4d1 tcp_init_metrics 5
ffffffff816d02b1 tcp_gro_complete 5
ffffffff816b81c1 tcp_free_fastopen_req 5
ffffffff816ca4e1 tcp_v4_destroy_sock 5
ffffffff816cddb1 tcp_cleanup_congestion_control 5
ffffffff816c67b1 tcp_send_fin 5
ffffffff816bd8e1 tcp_init_buffer_space 5
ffffffff816be801 tcp_init_cwnd 5
ffffffff816c1c51 tcp_select_initial_window 5
ffffffff816b8201 tcp_check_oom 5
ffffffff816c2a81 tcp_default_init_rwnd 5
ffffffff816cdc71 tcp_assign_congestion_control 5
ffffffff816b54b1 tcp_getsockopt 6
ffffffff816b3b21 tcp_ioctl 6
ffffffff816c2fe1 tcp_mtup_init 8
ffffffff816b96d1 tcp_parse_options 8
ffffffff816c2f91 tcp_mss_to_mtu 8
ffffffff816bd511 tcp_try_rmem_schedule 8
ffffffff816cf051 tcp_get_metrics 10
ffffffff816ba271 tcp_try_coalesce 10
ffffffff816c0de1 tcp_rcv_state_process 14
ffffffff816c2941 tcp_sync_mss 14
ffffffff816c7e31 tcp_write_timer_handler 15
ffffffff816c8001 tcp_write_timer 16
ffffffff816bb171 tcp_grow_window.isra.27 22
ffffffff816b45b1 tcp_set_state 23
ffffffff816c5921 tcp_send_ack 37
ffffffff816c7641 tcp_delack_timer 42
ffffffff816c7471 tcp_delack_timer_handler 42
ffffffff816c01f1 tcp_validate_incoming 91
ffffffff816b44f1 tcp_prequeue_process 112
ffffffff816cb8f1 tcp_v4_early_demux 117
ffffffff816d08b1 tcp_gro_receive 146
ffffffff816bb5e1 tcp_queue_rcv 167
ffffffff816bdb91 tcp_data_queue 215
ffffffff816ba321 tcp_urg 219
ffffffff816c6c81 tcp_send_delayed_ack 257
ffffffff816b3ee1 tcp_send_mss 275
ffffffff816b3dc1 tcp_push 275
ffffffff816b76c1 tcp_sendmsg 275
ffffffff816bb2a1 tcp_event_data_recv 275
ffffffff816c1d61 tcp_nagle_check 279
ffffffff816c3f11 tcp_write_xmit 282
ffffffff816c2341 tcp_event_new_data_sent 282
ffffffff816c3061 tcp_current_mss 284
ffffffff816c1db1 tcp_init_tso_segs 284
ffffffff816c2871 tcp_wfree 286
ffffffff816c3251 tcp_schedule_loss_probe 305
ffffffff816cb821 tcp_v4_send_check 323
ffffffff816c3581 tcp_transmit_skb 323
ffffffff816b54e1 tcp_recvmsg 323
ffffffff816c2111 tcp_options_write 325
ffffffff816bda61 tcp_rcv_space_adjust 328
ffffffff816bb721 tcp_check_space 332
ffffffff816c04a1 tcp_rcv_established 337
ffffffff816bee61 tcp_ack 337
ffffffff816b9611 tcp_parse_aligned_timestamp.part.43 345
ffffffff816cafc1 tcp_prequeue 346
ffffffff816cab21 tcp_v4_do_rcv 351
ffffffff816cba51 tcp_v4_rcv 351
ffffffff816b8b91 tcp_parse_md5sig_option 351
ffffffff816b3fb1 tcp_cleanup_rbuf 436
ffffffff816b64a1 tcp_poll 468
ffffffff816c1f01 tcp_established_options 604
ffffffff816c82f1 tcp_v4_md5_lookup 615
ffffffff816c4e11 tcp_release_cb 736
ffffffff816bec01 tcp_rearm_rto 843
ffffffff816c8261 tcp_md5_do_lookup 968
Detaching...
The current implementation can take many seconds to detach from tracing, after
Ctrl-C has been hit.
Couting all vfs functions for process ID 5276 only:
# ./funccount -p 5276 'vfs_*'
Tracing... Ctrl-C to end.
^C
ADDR FUNC COUNT
ffffffff811e8c71 vfs_getattr_nosec 7
ffffffff811e8d41 vfs_getattr 7
ffffffff811e8dd1 vfs_fstatat 11
ffffffff811e4251 vfs_read 12
ffffffff811e4381 vfs_write 16
Detaching...
This matches when that PID is on-CPU and the kernel function is called.
An interval can be provided. Eg, printing output every 1 second for vfs calls:
# ./funccount -i 1 'vfs_*'
Tracing... Ctrl-C to end.
ADDR FUNC COUNT
ffffffff811e8dd1 vfs_fstatat 1
ffffffff811e8d71 vfs_fstat 16
ffffffff811e8c71 vfs_getattr_nosec 17
ffffffff811e8d41 vfs_getattr 17
ffffffff811e4381 vfs_write 52
ffffffff811e4251 vfs_read 79
ffffffff811e3221 vfs_open 98
ADDR FUNC COUNT
ffffffff811e8dd1 vfs_fstatat 10
ffffffff811e8d71 vfs_fstat 10
ffffffff811e3221 vfs_open 13
ffffffff811e8c71 vfs_getattr_nosec 20
ffffffff811e8d41 vfs_getattr 20
ffffffff811e4381 vfs_write 28
ffffffff811e4251 vfs_read 39
ADDR FUNC COUNT
ffffffff81215191 vfs_fsync_range 2
ffffffff81231df1 vfs_lock_file 30
ffffffff811e4381 vfs_write 107
ffffffff811e8dd1 vfs_fstatat 129
ffffffff811e8d71 vfs_fstat 130
ffffffff811e3221 vfs_open 154
ffffffff811e8c71 vfs_getattr_nosec 222
ffffffff811e8d41 vfs_getattr 222
ffffffff811e4251 vfs_read 384
^C
ADDR FUNC COUNT
ffffffff811e4251 vfs_read 4
ffffffff811e4381 vfs_write 5
Detaching...
This can be useful for making some ad hoc tools, exposing new counts of
kernel activity that aren't visible in other metrics.
Include -T to print timestamps on output.
The "*" wildcard can be used multiple times. Eg, matching functions that contain
the word "readdir":
# ./funccount '*readdir*'
Tracing... Ctrl-C to end.
^C
ADDR FUNC COUNT
ffffffff81260911 ext4_readdir 4
Detaching...
Matching "tcp" then "send":
# ./funccount '*tcp*send*'
Tracing... Ctrl-C to end.
^C
ADDR FUNC COUNT
ffffffff816c5921 tcp_send_ack 4
ffffffff816c6c81 tcp_send_delayed_ack 19
ffffffff816b3ee1 tcp_send_mss 26
ffffffff816b76c1 tcp_sendmsg 26
ffffffff816cb821 tcp_v4_send_check 30
ffffffff816cb731 __tcp_v4_send_check 30
Detaching...
Regular expressions can also be used with the -r option. Eg:
# ./funccount -r '^vfs_[rw]'
Tracing... Ctrl-C to end.
^C
ADDR FUNC COUNT
ffffffff811e4381 vfs_write 26
ffffffff811e4251 vfs_read 42
Detaching...
Full USAGE:
# ./funccount -h
usage: funccount [-h] [-p PID] [-i INTERVAL] [-T] [-r] pattern
Count kernel function calls
positional arguments:
pattern search expression for kernel functions
optional arguments:
-h, --help show this help message and exit
-p PID, --pid PID trace this PID only
-i INTERVAL, --interval INTERVAL
summary interval, seconds
-T, --timestamp include timestamp on output
-r, --regexp use regular expressions. Default is "*" wildcards
only.
examples:
./funccount 'vfs_*' # count kernel functions starting with "vfs"
./funccount 'tcp_send*' # count kernel funcs starting with "tcp_send"
./funccount -r '^vfs.*' # same as above, using regular expressions
./funccount -Ti 5 'vfs_*' # output every 5 seconds, with timestamps
./funccount -p 185 'vfs_*' # count vfs calls for PID 181 only