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