[PATCH 2/2] perf: Document PERF_EVENT_IOC_SET_EVENT_LIMIT

[Charlie Jenkins]

Introduce PERF_EVENT_IOC_SET_EVENT_LIMIT and explain the differences
between it and PERF_EVENT_IOC_REFRESH.

Signed-off-by: Charlie Jenkins <charlie@xxxxxxxxxxxx>
---
 tools/perf/design.txt | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/tools/perf/design.txt b/tools/perf/design.txt
index aa8cfeabb743..1626ae83785a 100644
--- a/tools/perf/design.txt
+++ b/tools/perf/design.txt
@@ -439,6 +439,11 @@ Additionally, non-inherited overflow counters can use
 
 to enable a counter for 'nr' events, after which it gets disabled again.
 
+PERF_EVENT_IOC_REFRESH will increment the event limit by 'nr' and enable the
+event. To increment the event limit without enabling it, use the following:
+
+	ioctl(fd, PERF_EVENT_IOC_INC_EVENT_LIMIT, nr);
+
 A process can enable or disable all the counter groups that are
 attached to it, using prctl:
 

-- 
2.44.0