Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   Valentin Schneider <vschneid@redhat.com>
To:     linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
        linux-doc@vger.kernel.org
Cc:     Steven Rostedt <rostedt@goodmis.org>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Juri Lelli <juri.lelli@redhat.com>,
        Daniel Bristot de Oliveira <bristot@redhat.com>,
        Marcelo Tosatti <mtosatti@redhat.com>,
        Leonardo Bras <leobras@redhat.com>,
        Frederic Weisbecker <frederic@kernel.org>
Subject: [PATCH v2 6/9] tracing/filters: Optimise scalar vs cpumask filtering when the user mask is a single CPU
Date:   Fri,  7 Jul 2023 18:21:52 +0100
Message-Id: <20230707172155.70873-7-vschneid@redhat.com>
In-Reply-To: <20230707172155.70873-1-vschneid@redhat.com>
References: <20230707172155.70873-1-vschneid@redhat.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Steven noted that when the user-provided cpumask contains a single CPU,
then the filtering function can use a scalar as input instead of a
full-fledged cpumask.

When the mask contains a single CPU, directly re-use the unsigned field
predicate functions. Transform '&' into '==' beforehand.

Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Valentin Schneider <vschneid@redhat.com>
---
 kernel/trace/trace_events_filter.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 2fe65ddeb34ef..54d642fabb7f1 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -1750,7 +1750,7 @@ static int parse_pred(const char *str, void *data,
 		 * then we can treat it as a scalar input.
 		 */
 		single = cpumask_weight(pred->mask) == 1;
-		if (single && field->filter_type == FILTER_CPUMASK) {
+		if (single && field->filter_type != FILTER_CPU) {
 			pred->val = cpumask_first(pred->mask);
 			kfree(pred->mask);
 		}
@@ -1761,6 +1761,11 @@ static int parse_pred(const char *str, void *data,
 				FILTER_PRED_FN_CPUMASK;
 		} else if (field->filter_type == FILTER_CPU) {
 			pred->fn_num = FILTER_PRED_FN_CPU_CPUMASK;
+		} else if (single) {
+			pred->op = pred->op == OP_BAND ? OP_EQ : pred->op;
+			pred->fn_num = select_comparison_fn(pred->op, field->size, false);
+			if (pred->op == OP_NE)
+				pred->not = 1;
 		} else {
 			switch (field->size) {
 			case 8:
-- 
2.31.1