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Wed, 03 Sep 2025 00:52:06 -0700 (PDT) From: Jinchao Wang To: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , "Liang, Kan" , linux-perf-users@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Jinchao Wang Subject: [PATCH 3/3] perf/hw_breakpoint: Skip modify_bp_slot() if slot index unchanged Date: Wed, 3 Sep 2025 15:51:40 +0800 Message-ID: <20250903075144.3722848-3-wangjinchao600@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250903075144.3722848-1-wangjinchao600@gmail.com> References: <20250903075144.3722848-1-wangjinchao600@gmail.com> Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Only call modify_bp_slot() when the old and new breakpoint types map to different slot indices. This avoids unnecessary release/reserve operations and improves efficiency. Signed-off-by: Jinchao Wang --- kernel/events/hw_breakpoint.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c index 1db2c5e24d0e..6fed9521baf2 100644 --- a/kernel/events/hw_breakpoint.c +++ b/kernel/events/hw_breakpoint.c @@ -752,6 +752,7 @@ modify_user_hw_breakpoint_check(struct perf_event *bp, struct perf_event_attr *a { struct arch_hw_breakpoint hw = { }; int err; + enum bp_type_idx old_type_idx, new_type_idx; err = hw_breakpoint_parse(bp, attr, &hw); if (err) @@ -766,7 +767,9 @@ modify_user_hw_breakpoint_check(struct perf_event *bp, struct perf_event_attr *a return -EINVAL; } - if (bp->attr.bp_type != attr->bp_type) { + old_type_idx = find_slot_idx(bp->attr.bp_type); + new_type_idx = find_slot_idx(attr->bp_type); + if (old_type_idx != new_type_idx) { err = modify_bp_slot(bp, bp->attr.bp_type, attr->bp_type); if (err) return err; -- 2.43.0