1		i	synthesize instructions events
2		b	synthesize branches events
3		c	synthesize branches events (calls only)
4		r	synthesize branches events (returns only)
5		x	synthesize transactions events
6		w	synthesize ptwrite events
7		p	synthesize power events
8		e	synthesize error events
9		d	create a debug log
10		g	synthesize a call chain (use with i or x)
11		l	synthesize last branch entries (use with i or x)
12		s       skip initial number of events
13
14	The default is all events i.e. the same as --itrace=ibxwpe,
15	except for perf script where it is --itrace=ce
16
17	In addition, the period (default 100000, except for perf script where it is 1)
18	for instructions events can be specified in units of:
19
20		i	instructions
21		t	ticks
22		ms	milliseconds
23		us	microseconds
24		ns	nanoseconds (default)
25
26	Also the call chain size (default 16, max. 1024) for instructions or
27	transactions events can be specified.
28
29	Also the number of last branch entries (default 64, max. 1024) for
30	instructions or transactions events can be specified.
31
32	It is also possible to skip events generated (instructions, branches, transactions,
33	ptwrite, power) at the beginning. This is useful to ignore initialization code.
34
35	--itrace=i0nss1000000
36
37	skips the first million instructions.
38