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From: Namhyung Kim <namhyung@kernel.org>
To: Arnaldo Carvalho de Melo <acme@kernel.org>,
	Ian Rogers <irogers@google.com>,
	Kan Liang <kan.liang@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>,
	Adrian Hunter <adrian.hunter@intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-perf-users@vger.kernel.org, Song Liu <song@kernel.org>,
	bpf@vger.kernel.org
Subject: [PATCH 2/3] perf lock contention: Simplify spinlock check
Date: Thu, 29 Aug 2024 23:51:49 -0700	[thread overview]
Message-ID: <20240830065150.1758962-2-namhyung@kernel.org> (raw)
In-Reply-To: <20240830065150.1758962-1-namhyung@kernel.org>

The LCB_F_SPIN bit is used for spinlock, rwlock and optimistic spinning
in mutex.  In get_tstamp_elem() it needs to check spinlock and rwlock
only.  As mutex sets the LCB_F_MUTEX, it can check those two bits and
reduce the number of operations.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 tools/perf/util/bpf_skel/lock_contention.bpf.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c
index e8a6f6463019..4b7237e178bd 100644
--- a/tools/perf/util/bpf_skel/lock_contention.bpf.c
+++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c
@@ -323,8 +323,7 @@ static inline struct tstamp_data *get_tstamp_elem(__u32 flags)
 	struct tstamp_data *pelem;
 
 	/* Use per-cpu array map for spinlock and rwlock */
-	if (flags == (LCB_F_SPIN | LCB_F_READ) || flags == LCB_F_SPIN ||
-	    flags == (LCB_F_SPIN | LCB_F_WRITE)) {
+	if ((flags & (LCB_F_SPIN | LCB_F_MUTEX)) == LCB_F_SPIN) {
 		__u32 idx = 0;
 
 		pelem = bpf_map_lookup_elem(&tstamp_cpu, &idx);
-- 
2.46.0.469.g59c65b2a67-goog


  reply	other threads:[~2024-08-30  6:51 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-08-30  6:51 [PATCH 1/3] perf lock contention: Handle error in a single place Namhyung Kim
2024-08-30  6:51 ` Namhyung Kim [this message]
2024-08-30  6:51 ` [PATCH 3/3] perf lock contention: Do not fail EEXIST for update Namhyung Kim
2024-08-30 13:17 ` [PATCH 1/3] perf lock contention: Handle error in a single place Arnaldo Carvalho de Melo

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