Hi Peter,

-----Original Message-----
From: Peter Zijlstra [mailto:peterz@infradead.org]
Sent: 19 августа 2015 г. 2:37
To: Alexey Brodkin
Cc: linux-arch@vger.kernel.org; linux-kernel@vger.kernel.org; Vineet.Gupta1@synopsys.com; arc-linux-dev@synopsys.com;
arnd@arndb.de; Arnaldo Carvalho de Melo
Subject: Re: [PATCH v2 6/8] ARCv2: perf: implement exclusion of event counting in user or kernel mode

On Wed, Aug 05, 2015 at 06:13:32PM +0300, Alexey Brodkin wrote:

quoted

+	hwc->config = 0;
+
+	if (is_isa_arcv2()) {
+		/* "exclude user" means "count only kernel" */
+		if (event->attr.exclude_user)
+			hwc->config |= ARC_REG_PCT_CONFIG_KERN;
+
+		/* "exclude kernel" means "count only user" */
+		if (event->attr.exclude_kernel)
+			hwc->config |= ARC_REG_PCT_CONFIG_USER;
+	}
+
 	switch (event->attr.type) {
 	case PERF_TYPE_HARDWARE:
 		if (event->attr.config >= PERF_COUNT_HW_MAX)
 			return -ENOENT;
 		if (arc_pmu->ev_hw_idx[event->attr.config] < 0)
 			return -ENOENT;
-		hwc->config = arc_pmu->ev_hw_idx[event->attr.config];
+		hwc->config |= arc_pmu->ev_hw_idx[event->attr.config];

So I would still very much like perf_event_attr::config to reflect the
value you'll program into hardware.

If you want to do that weird 4 character lookup thing, use a special
hardware event (possibly 0 if that is not a valid value), and stuff the
4 chars in ::config1

Ok I understand your concern here but I cannot quite understand
what do you mean saying "stuff the 4 chars in ::config1".

Could you please explain this a bit more verbose?
Is there an example of something similar I may take a look at?

-Alexey