bpftool: Documentation for bpftool prog profile

Add documentation for the new bpftool prog profile command.
Signed-off-by: NSong Liu <songliubraving@fb.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Reviewed-by: NQuentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20200309173218.2739965-3-songliubraving@fb.com

tools/bpf/bpftool/Documentation/bpftool-prog.rst

@@ -30,6 +30,7 @@ PROG COMMANDS
 |	**bpftool** **prog detach** *PROG* *ATTACH_TYPE* [*MAP*]
 |	**bpftool** **prog tracelog**
 |	**bpftool** **prog run** *PROG* **data_in** *FILE* [**data_out** *FILE* [**data_size_out** *L*]] [**ctx_in** *FILE* [**ctx_out** *FILE* [**ctx_size_out** *M*]]] [**repeat** *N*]
+|	**bpftool** **prog profile** *PROG* [**duration** *DURATION*] *METRICs*
 |	**bpftool** **prog help**
 |
 |	*MAP* := { **id** *MAP_ID* | **pinned** *FILE* }
@@ -48,6 +49,9 @@ PROG COMMANDS
 |       *ATTACH_TYPE* := {
 |		**msg_verdict** | **stream_verdict** | **stream_parser** | **flow_dissector**
 |	}
+|	*METRIC* := {
+|		**cycles** | **instructions** | **l1d_loads** | **llc_misses**
+|	}
 
 
 DESCRIPTION
@@ -189,6 +193,12 @@ DESCRIPTION
 		  not all of them can take the **ctx_in**/**ctx_out**
 		  arguments. bpftool does not perform checks on program types.
 
+	**bpftool prog profile** *PROG* [**duration** *DURATION*] *METRICs*
+		  Profile *METRICs* for bpf program *PROG* for *DURATION*
+		  seconds or until user hits Ctrl-C. *DURATION* is optional.
+		  If *DURATION* is not specified, the profiling will run up to
+		  UINT_MAX seconds.
+
 	**bpftool prog help**
 		  Print short help message.
 
@@ -311,6 +321,15 @@ EXAMPLES
 
 **# rm /sys/fs/bpf/xdp1**
 
+|
+| **# bpftool prog profile id 337 duration 10 cycles instructions llc_misses**
+
+::
+         51397 run_cnt
+      40176203 cycles                                                 (83.05%)
+      42518139 instructions    #   1.06 insns per cycle               (83.39%)
+           123 llc_misses      #   2.89 LLC misses per million insns  (83.15%)
+
 SEE ALSO
 ========
 	**bpf**\ (2),