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From: Charlie Jenkins <charlie@rivosinc.com>
To: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	 Arnaldo Carvalho de Melo <acme@kernel.org>,
	 Namhyung Kim <namhyung@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	 Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	 Jiri Olsa <jolsa@kernel.org>, Ian Rogers <irogers@google.com>,
	 Adrian Hunter <adrian.hunter@intel.com>,
	Atish Patra <atishp@rivosinc.com>
Cc: linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
	 Charlie Jenkins <charlie@rivosinc.com>
Subject: [PATCH 2/2] perf: Document PERF_EVENT_IOC_SET_EVENT_LIMIT
Date: Wed, 24 Jul 2024 15:54:12 -0700	[thread overview]
Message-ID: <20240724-perf_set_event_limit-v1-2-e680c93eca55@rivosinc.com> (raw)
In-Reply-To: <20240724-perf_set_event_limit-v1-0-e680c93eca55@rivosinc.com>

Introduce PERF_EVENT_IOC_SET_EVENT_LIMIT and explain the differences
between it and PERF_EVENT_IOC_REFRESH.

Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
---
 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


  parent reply	other threads:[~2024-07-24 22:54 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-07-24 22:54 [PATCH 0/2] perf: Add PERF_EVENT_IOC_SET_EVENT_LIMIT Charlie Jenkins
2024-07-24 22:54 ` [PATCH 1/2] perf: Add PERF_EVENT_IOC_INC_EVENT_LIMIT Charlie Jenkins
2024-07-24 22:54 ` Charlie Jenkins [this message]
2024-07-29 21:19 ` [PATCH 0/2] perf: Add PERF_EVENT_IOC_SET_EVENT_LIMIT Charlie Jenkins

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