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Demonstrations of funccount, the Linux eBPF/bcc version.
This program traces functions, tracepoints, or USDT probes that match a
specified pattern, and when Ctrl-C is hit prints a summary of their count
while tracing. Eg, tracing all kernel functions that begin with "vfs_":
# ./funccount 'vfs_*'
Tracing... Ctrl-C to end.
^C
FUNC COUNT
vfs_create 1
vfs_rename 1
vfs_fsync_range 2
vfs_lock_file 30
vfs_fstatat 152
vfs_fstat 154
vfs_write 166
vfs_getattr_nosec 262
vfs_getattr 262
vfs_open 264
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
FUNC COUNT
tcp_try_undo_recovery 1
tcp_twsk_destructor 1
tcp_enter_recovery 1
tcp_xmit_retransmit_queue 1
tcp_update_scoreboard 1
tcp_verify_retransmit_hint 1
tcp_tsq_handler.part.31 1
tcp_sacktag_write_queue 1
tcp_match_skb_to_sack 1
tcp_time_wait 1
tcp_mark_head_lost 1
tcp_init_cwnd_reduction 1
tcp_sacktag_one 1
tcp_sacktag_walk 1
tcp_retransmit_skb 1
tcp_tasklet_func 1
tcp_resume_early_retransmit 1
tcp_dsack_set 1
tcp_v4_syn_recv_sock 2
tcp_ca_openreq_child 2
tcp_try_fastopen 2
tcp_openreq_init_rwin 2
tcp_v4_init_req 2
tcp_create_openreq_child 2
tcp_v4_send_synack 2
tcp_v4_init_sequence 2
tcp_fragment 2
tcp_v4_conn_request 2
tcp_conn_request 2
tcp_v4_route_req 2
tcp_fragment_tstamp 2
tcp_try_keep_open 2
tcp_v4_reqsk_destructor 2
tcp_may_send_now 2
tcp_make_synack 2
tcp_child_process 2
tcp_check_req 2
tcp_fastretrans_alert 2
tcp_set_keepalive 2
tcp_finish_connect 3
tcp_connect_queue_skb 3
tcp_v4_connect 3
tcp_init_sock 3
tcp_v4_init_sock 3
tcp_connect 3
tcp_any_retrans_done.part.35 3
tcp_clear_retrans 3
tcp_setsockopt 4
tcp_update_metrics 5
tcp_done 5
tcp_initialize_rcv_mss 5
tcp_sndbuf_expand 5
tcp_fin 5
tcp_init_xmit_timers 5
tcp_close 5
tcp_init_congestion_control 5
tcp_init_metrics 5
tcp_gro_complete 5
tcp_free_fastopen_req 5
tcp_v4_destroy_sock 5
tcp_cleanup_congestion_control 5
tcp_send_fin 5
tcp_init_buffer_space 5
tcp_init_cwnd 5
tcp_select_initial_window 5
tcp_check_oom 5
tcp_default_init_rwnd 5
tcp_assign_congestion_control 5
tcp_getsockopt 6
tcp_ioctl 6
tcp_mtup_init 8
tcp_parse_options 8
tcp_mss_to_mtu 8
tcp_try_rmem_schedule 8
tcp_get_metrics 10
tcp_try_coalesce 10
tcp_rcv_state_process 14
tcp_sync_mss 14
tcp_write_timer_handler 15
tcp_write_timer 16
tcp_grow_window.isra.27 22
tcp_set_state 23
tcp_send_ack 37
tcp_delack_timer 42
tcp_delack_timer_handler 42
tcp_validate_incoming 91
tcp_prequeue_process 112
tcp_v4_early_demux 117
tcp_gro_receive 146
tcp_queue_rcv 167
tcp_data_queue 215
tcp_urg 219
tcp_send_delayed_ack 257
tcp_send_mss 275
tcp_push 275
tcp_sendmsg 275
tcp_event_data_recv 275
tcp_nagle_check 279
tcp_write_xmit 282
tcp_event_new_data_sent 282
tcp_current_mss 284
tcp_init_tso_segs 284
tcp_wfree 286
tcp_schedule_loss_probe 305
tcp_v4_send_check 323
tcp_transmit_skb 323
tcp_recvmsg 323
tcp_options_write 325
tcp_rcv_space_adjust 328
tcp_check_space 332
tcp_rcv_established 337
tcp_ack 337
tcp_parse_aligned_timestamp.part.43 345
tcp_prequeue 346
tcp_v4_do_rcv 351
tcp_v4_rcv 351
tcp_parse_md5sig_option 351
tcp_cleanup_rbuf 436
tcp_poll 468
tcp_established_options 604
tcp_v4_md5_lookup 615
tcp_release_cb 736
tcp_rearm_rto 843
tcp_md5_do_lookup 968
Detaching...
The current implementation can take many seconds to detach from tracing, after
Ctrl-C has been hit.
User functions can be traced in executables or libraries, and per-process
filtering is allowed:
# ./funccount -p 1442 /home/ubuntu/contentions:*
Tracing 15 functions for "/home/ubuntu/contentions:*"... Hit Ctrl-C to end.
^C
FUNC COUNT
main 1
_start 1
primes_thread 2
insert_result 87186
is_prime 1252772
Detaching...
If /home/ubuntu is in the $PATH, then the following command will also work:
# ./funccount -p 1442 contentions:*
Counting libc write and read calls using regular expression syntax (-r):
# ./funccount -r 'c:(write|read)$'
Tracing 2 functions for "c:(write|read)$"... Hit Ctrl-C to end.
^C
FUNC COUNT
read 2
write 4
Detaching...
Kernel tracepoints are also available as targets. For example, trace common
block I/O tracepoints and see how often they are invoked:
# ./funccount t:block:*
Tracing 19 functions for "t:block:*"... Hit Ctrl-C to end.
^C
FUNC COUNT
block:block_rq_complete 7
block:block_rq_issue 7
block:block_getrq 7
block:block_rq_insert 7
Detaching...
Likewise, user-mode statically defined traces (USDT) can also be probed. For
example, count mutex-related events in pthreads:
# ./funccount u:pthread:*mutex* -p 1442
Tracing 7 functions for "u:pthread:*mutex*"... Hit Ctrl-C to end.
^C
FUNC COUNT
mutex_init 1
mutex_entry 547122
mutex_acquired 547175
mutex_release 547185
Detaching...
An interval can be provided. Eg, printing output every 1 second for vfs calls:
# ./funccount -i 1 'vfs_*'
Tracing... Ctrl-C to end.
FUNC COUNT
vfs_fstatat 1
vfs_fstat 16
vfs_getattr_nosec 17
vfs_getattr 17
vfs_write 52
vfs_read 79
vfs_open 98
FUNC COUNT
vfs_fstatat 10
vfs_fstat 10
vfs_open 13
vfs_getattr_nosec 20
vfs_getattr 20
vfs_write 28
vfs_read 39
FUNC COUNT
vfs_fsync_range 2
vfs_lock_file 30
vfs_write 107
vfs_fstatat 129
vfs_fstat 130
vfs_open 154
vfs_getattr_nosec 222
vfs_getattr 222
vfs_read 384
^C
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.
A maximum duration can be set. For example, to print 5 x 1 second summaries
of vfs_read() calls:
# ./funccount -i 1 -d 5 vfs_read
Tracing 1 functions for "vfs_read"... Hit Ctrl-C to end.
FUNC COUNT
vfs_read 30
FUNC COUNT
vfs_read 26
FUNC COUNT
vfs_read 54
FUNC COUNT
vfs_read 25
FUNC COUNT
vfs_read 31
Detaching...
By leaving off the "-i 1", this will print a single 5 second summary:
# funccount.py -d 5 vfs_read
Tracing 1 functions for "vfs_read"... Hit Ctrl-C to end.
FUNC COUNT
vfs_read 167
Detaching...
This can be useful for finding out rates: trace all functions for ten seconds
and then divide by ten for the per-second rate.
The "*" wildcard can be used multiple times. Eg, matching functions that contain
the word "readdir":
# ./funccount '*readdir*'
Tracing... Ctrl-C to end.
^C
FUNC COUNT
ext4_readdir 4
Detaching...
Matching "tcp" then "send":
# ./funccount '*tcp*send*'
Tracing... Ctrl-C to end.
^C
FUNC COUNT
tcp_send_ack 4
tcp_send_delayed_ack 19
tcp_send_mss 26
tcp_sendmsg 26
tcp_v4_send_check 30
__tcp_v4_send_check 30
Detaching...
A cpu is specified by "-c CPU", this will only trace the specified CPU. Eg,
trace how many timers setting per second of CPU 1 on a x86(Intel) server:
# funccount.py -i 1 -c 1 lapic_next_deadline
Tracing 1 functions for "lapic_next_deadline"... Hit Ctrl-C to end.
FUNC COUNT
lapic_next_deadline 3840
FUNC COUNT
lapic_next_deadline 3930
FUNC COUNT
lapic_next_deadline 4701
FUNC COUNT
lapic_next_deadline 5895
FUNC COUNT
lapic_next_deadline 5591
FUNC COUNT
lapic_next_deadline 4727
FUNC COUNT
lapic_next_deadline 5560
FUNC COUNT
lapic_next_deadline 5416
^C
FUNC COUNT
lapic_next_deadline 372
Detaching...
Full USAGE:
# ./funccount -h
usage: funccount.py [-h] [-p PID] [-i INTERVAL] [-d DURATION] [-T] [-r] [-D]
[-c CPU]
pattern
Count functions, tracepoints, and USDT probes
positional arguments:
pattern search expression for events
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
-d DURATION, --duration DURATION
total duration of trace, seconds
-T, --timestamp include timestamp on output
-r, --regexp use regular expressions. Default is "*" wildcards
only.
-D, --debug print BPF program before starting (for debugging
purposes)
-c CPU, --cpu CPU trace this CPU only
examples:
./funccount 'vfs_*' # count kernel fns starting with "vfs"
./funccount -r '^vfs.*' # same as above, using regular expressions
./funccount -Ti 5 'vfs_*' # output every 5 seconds, with timestamps
./funccount -d 10 'vfs_*' # trace for 10 seconds only
./funccount -p 185 'vfs_*' # count vfs calls for PID 181 only
./funccount t:sched:sched_fork # count calls to the sched_fork tracepoint
./funccount -p 185 u:node:gc* # count all GC USDT probes in node, PID 185
./funccount c:malloc # count all malloc() calls in libc
./funccount go:os.* # count all "os.*" calls in libgo
./funccount -p 185 go:os.* # count all "os.*" calls in libgo, PID 185
./funccount ./test:read* # count "read*" calls in the ./test binary
./funccount -c 1 'vfs_*' # count vfs calls on CPU 1 only