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Message-Id: <20230720163056.2564824-6-vschneid@redhat.com>
Date: Thu, 20 Jul 2023 17:30:41 +0100
From: Valentin Schneider <vschneid@...hat.com>
To: linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
linux-doc@...r.kernel.org, kvm@...r.kernel.org, linux-mm@...ck.org,
bpf@...r.kernel.org, x86@...nel.org, rcu@...r.kernel.org,
linux-kselftest@...r.kernel.org
Cc: Steven Rostedt <rostedt@...dmis.org>,
Masami Hiramatsu <mhiramat@...nel.org>,
Jonathan Corbet <corbet@....net>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>,
"H. Peter Anvin" <hpa@...or.com>,
Paolo Bonzini <pbonzini@...hat.com>,
Wanpeng Li <wanpengli@...cent.com>,
Vitaly Kuznetsov <vkuznets@...hat.com>,
Andy Lutomirski <luto@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
Frederic Weisbecker <frederic@...nel.org>,
"Paul E. McKenney" <paulmck@...nel.org>,
Neeraj Upadhyay <quic_neeraju@...cinc.com>,
Joel Fernandes <joel@...lfernandes.org>,
Josh Triplett <josh@...htriplett.org>,
Boqun Feng <boqun.feng@...il.com>,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
Lai Jiangshan <jiangshanlai@...il.com>,
Zqiang <qiang.zhang1211@...il.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Uladzislau Rezki <urezki@...il.com>,
Christoph Hellwig <hch@...radead.org>,
Lorenzo Stoakes <lstoakes@...il.com>,
Josh Poimboeuf <jpoimboe@...nel.org>,
Jason Baron <jbaron@...mai.com>,
Kees Cook <keescook@...omium.org>,
Sami Tolvanen <samitolvanen@...gle.com>,
Ard Biesheuvel <ardb@...nel.org>,
Nicholas Piggin <npiggin@...il.com>,
Juerg Haefliger <juerg.haefliger@...onical.com>,
Nicolas Saenz Julienne <nsaenz@...nel.org>,
"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
Nadav Amit <namit@...are.com>,
Dan Carpenter <error27@...il.com>,
Chuang Wang <nashuiliang@...il.com>,
Yang Jihong <yangjihong1@...wei.com>,
Petr Mladek <pmladek@...e.com>,
"Jason A. Donenfeld" <Jason@...c4.com>, Song Liu <song@...nel.org>,
Julian Pidancet <julian.pidancet@...cle.com>,
Tom Lendacky <thomas.lendacky@....com>,
Dionna Glaze <dionnaglaze@...gle.com>,
Thomas Weißschuh <linux@...ssschuh.net>,
Juri Lelli <juri.lelli@...hat.com>,
Daniel Bristot de Oliveira <bristot@...hat.com>,
Marcelo Tosatti <mtosatti@...hat.com>,
Yair Podemsky <ypodemsk@...hat.com>
Subject: [RFC PATCH v2 05/20] tracing/filters: Optimise cpumask vs cpumask filtering when user mask is a single CPU
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.
Reuse do_filter_scalar_cpumask() when the input mask has a weight of one.
Suggested-by: Steven Rostedt <rostedt@...dmis.org>
Signed-off-by: Valentin Schneider <vschneid@...hat.com>
---
kernel/trace/trace_events_filter.c | 35 +++++++++++++++++++++++++++++-
1 file changed, 34 insertions(+), 1 deletion(-)
diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 3009d0c61b532..2fe65ddeb34ef 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -70,6 +70,7 @@ enum filter_pred_fn {
FILTER_PRED_FN_CPU,
FILTER_PRED_FN_CPU_CPUMASK,
FILTER_PRED_FN_CPUMASK,
+ FILTER_PRED_FN_CPUMASK_CPU,
FILTER_PRED_FN_FUNCTION,
FILTER_PRED_FN_,
FILTER_PRED_TEST_VISITED,
@@ -957,6 +958,22 @@ static int filter_pred_cpumask(struct filter_pred *pred, void *event)
return do_filter_cpumask(pred->op, mask, cmp);
}
+/* Filter predicate for cpumask field vs user-provided scalar */
+static int filter_pred_cpumask_cpu(struct filter_pred *pred, void *event)
+{
+ u32 item = *(u32 *)(event + pred->offset);
+ int loc = item & 0xffff;
+ const struct cpumask *mask = (event + loc);
+ unsigned int cpu = pred->val;
+
+ /*
+ * This inverts the usual usage of the function (field is first element,
+ * user parameter is second), but that's fine because the (scalar, mask)
+ * operations used are symmetric.
+ */
+ return do_filter_scalar_cpumask(pred->op, cpu, mask);
+}
+
/* Filter predicate for COMM. */
static int filter_pred_comm(struct filter_pred *pred, void *event)
{
@@ -1453,6 +1470,8 @@ static int filter_pred_fn_call(struct filter_pred *pred, void *event)
return filter_pred_cpu_cpumask(pred, event);
case FILTER_PRED_FN_CPUMASK:
return filter_pred_cpumask(pred, event);
+ case FILTER_PRED_FN_CPUMASK_CPU:
+ return filter_pred_cpumask_cpu(pred, event);
case FILTER_PRED_FN_FUNCTION:
return filter_pred_function(pred, event);
case FILTER_PRED_TEST_VISITED:
@@ -1666,6 +1685,7 @@ static int parse_pred(const char *str, void *data,
} else if (!strncmp(str + i, "CPUS", 4)) {
unsigned int maskstart;
+ bool single;
char *tmp;
switch (field->filter_type) {
@@ -1724,8 +1744,21 @@ static int parse_pred(const char *str, void *data,
/* Move along */
i++;
+
+ /*
+ * Optimisation: if the user-provided mask has a weight of one
+ * then we can treat it as a scalar input.
+ */
+ single = cpumask_weight(pred->mask) == 1;
+ if (single && field->filter_type == FILTER_CPUMASK) {
+ pred->val = cpumask_first(pred->mask);
+ kfree(pred->mask);
+ }
+
if (field->filter_type == FILTER_CPUMASK) {
- pred->fn_num = FILTER_PRED_FN_CPUMASK;
+ pred->fn_num = single ?
+ FILTER_PRED_FN_CPUMASK_CPU :
+ FILTER_PRED_FN_CPUMASK;
} else if (field->filter_type == FILTER_CPU) {
pred->fn_num = FILTER_PRED_FN_CPU_CPUMASK;
} else {
--
2.31.1
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