linux/samples/bpf
Alexei Starovoitov 5c7fc2d27d samples/bpf: Add IO latency analysis (iosnoop/heatmap) tool
BPF C program attaches to
blk_mq_start_request()/blk_update_request() kprobe events to
calculate IO latency.

For every completed block IO event it computes the time delta
in nsec and records in a histogram map:

	map[log10(delta)*10]++

User space reads this histogram map every 2 seconds and prints
it as a 'heatmap' using gray shades of text terminal. Black
spaces have many events and white spaces have very few events.
Left most space is the smallest latency, right most space is
the largest latency in the range.

Usage:

	$ sudo ./tracex3
	and do 'sudo dd if=/dev/sda of=/dev/null' in other terminal.

Observe IO latencies and how different activity (like 'make
kernel') affects it.

Similar experiments can be done for network transmit latencies,
syscalls, etc.

'-t' flag prints the heatmap using normal ascii characters:

$ sudo ./tracex3 -t
  heatmap of IO latency
  # - many events with this latency
    - few events
	|1us      |10us     |100us    |1ms      |10ms     |100ms    |1s |10s
				 *ooo. *O.#.                                    # 221
			      .  *#     .                                       # 125
				 ..   .o#*..                                    # 55
			    .  . .  .  .#O                                      # 37
				 .#                                             # 175
				       .#*.                                     # 37
				  #                                             # 199
		      .              . *#*.                                     # 55
				       *#..*                                    # 42
				  #                                             # 266
			      ...***Oo#*OO**o#* .                               # 629
				  #                                             # 271
				      . .#o* o.*o*                              # 221
				. . o* *#O..                                    # 50

Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: David S. Miller <davem@davemloft.net>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1427312966-8434-9-git-send-email-ast@plumgrid.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-04-02 13:25:51 +02:00
..
bpf_helpers.h samples/bpf: Add simple non-portable kprobe filter example 2015-04-02 13:25:50 +02:00
bpf_load.c samples/bpf: Add simple non-portable kprobe filter example 2015-04-02 13:25:50 +02:00
bpf_load.h samples/bpf: Add simple non-portable kprobe filter example 2015-04-02 13:25:50 +02:00
libbpf.c samples/bpf: Add simple non-portable kprobe filter example 2015-04-02 13:25:50 +02:00
libbpf.h samples/bpf: Add simple non-portable kprobe filter example 2015-04-02 13:25:50 +02:00
Makefile samples/bpf: Add IO latency analysis (iosnoop/heatmap) tool 2015-04-02 13:25:51 +02:00
sock_example.c samples/bpf: Add simple non-portable kprobe filter example 2015-04-02 13:25:50 +02:00
sockex1_kern.c samples: bpf: trivial eBPF program in C 2014-12-05 21:47:33 -08:00
sockex1_user.c samples: bpf: trivial eBPF program in C 2014-12-05 21:47:33 -08:00
sockex2_kern.c samples: bpf: large eBPF program in C 2014-12-05 21:47:34 -08:00
sockex2_user.c samples: bpf: large eBPF program in C 2014-12-05 21:47:34 -08:00
test_maps.c samples: bpf: relax test_maps check 2015-01-26 17:20:40 -08:00
test_verifier.c samples/bpf: Add simple non-portable kprobe filter example 2015-04-02 13:25:50 +02:00
tracex1_kern.c samples/bpf: Add simple non-portable kprobe filter example 2015-04-02 13:25:50 +02:00
tracex1_user.c samples/bpf: Add simple non-portable kprobe filter example 2015-04-02 13:25:50 +02:00
tracex2_kern.c samples/bpf: Add counting example for kfree_skb() function calls and the write() syscall 2015-04-02 13:25:50 +02:00
tracex2_user.c samples/bpf: Add counting example for kfree_skb() function calls and the write() syscall 2015-04-02 13:25:50 +02:00
tracex3_kern.c samples/bpf: Add IO latency analysis (iosnoop/heatmap) tool 2015-04-02 13:25:51 +02:00
tracex3_user.c samples/bpf: Add IO latency analysis (iosnoop/heatmap) tool 2015-04-02 13:25:51 +02:00