From mboxrd@z Thu Jan  1 00:00:00 1970
From: Pawel Moll <pawel.moll-5wv7dgnIgG8@public.gmane.org>
Subject: Re: [RFC 2/2] perf: Marker software event and ioctl
Date: Fri, 12 Sep 2014 14:58:55 +0100
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To: Arnaldo Carvalho de Melo <acme-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: Christopher Covington <cov-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>, Richard Cochran <richardcochran-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Steven Rostedt <rostedt-nx8X9YLhiw1AfugRpC6u6w@public.gmane.org>, Ingo Molnar <mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, Peter Zijlstra <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>, Paul Mackerras <paulus-eUNUBHrolfbYtjvyW6yDsg@public.gmane.org>, John Stultz <john.stultz-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>, "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, "linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" <linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
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On Fri, 2014-09-12 at 14:49 +0100, Arnaldo Carvalho de Melo wrote:
> Perhaps both? I.e. an u64 followed from a string, if the u64 is zero,
> then there is a string right after it?

How would this look like in userspace? Something like this?

8<----
struct perf_event_marker {
	uint64_t value;
	char *string;
} arg;

arg.value =3D 0x1234;

/* or */

arg.value =3D 0;
arg.string =3D "abcd";

ioctl(fd, PERF_EVENT_IOC_MARKER, &arg)
8<----

If so, maybe it would simpler just to go for classic size/data
structure?

8<-----
struct perf_event_marker {
	uint32_t size;
	void *data;
}
8<-----

This would directly map into struct perf_raw_record...

Pawe=C5=82