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From:   Valentin Schneider <vschneid@redhat.com>
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Cc:     "Paul E. McKenney" <paulmck@kernel.org>,
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        Dave Hansen <dave.hansen@linux.intel.com>,
        "H. Peter Anvin" <hpa@zytor.com>, Marc Zyngier <maz@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Russell King <linux@armlinux.org.uk>,
        Nicholas Piggin <npiggin@gmail.com>,
        Guo Ren <guoren@kernel.org>,
        "David S. Miller" <davem@davemloft.net>
Subject: [RFC PATCH 2/5] sched, smp: Trace send_call_function_single_ipi()
Date:   Fri,  7 Oct 2022 16:45:30 +0100
Message-Id: <20221007154533.1878285-2-vschneid@redhat.com>
In-Reply-To: <20221007154145.1877054-1-vschneid@redhat.com>
References: <20221007154145.1877054-1-vschneid@redhat.com>
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send_call_function_single_ipi() is the thing that sends IPIs at the bottom
of smp_call_function*() via either generic_exec_single() or
smp_call_function_many_cond(). Give it an IPI-related tracepoint.

Note that this ends up tracing any IPI sent via __smp_call_single_queue(),
which covers __ttwu_queue_wakelist() and irq_work_queue_on() "for free".

Signed-off-by: Valentin Schneider <vschneid@redhat.com>
---
 arch/arm/kernel/smp.c   | 3 ---
 arch/arm64/kernel/smp.c | 1 -
 kernel/sched/core.c     | 7 +++++--
 kernel/smp.c            | 4 ++++
 4 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index 978db2d96b44..3b280d55c1c4 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -48,9 +48,6 @@
 #include <asm/mach/arch.h>
 #include <asm/mpu.h>
 
-#define CREATE_TRACE_POINTS
-#include <trace/events/ipi.h>
-
 /*
  * as from 2.5, kernels no longer have an init_tasks structure
  * so we need some other way of telling a new secondary core
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index ffc5d76cf695..937d2623e06b 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -51,7 +51,6 @@
 #include <asm/ptrace.h>
 #include <asm/virt.h>
 
-#define CREATE_TRACE_POINTS
 #include <trace/events/ipi.h>
 
 DEFINE_PER_CPU_READ_MOSTLY(int, cpu_number);
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 60fdc0faf1c9..14e5e137172f 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -81,6 +81,7 @@
 #include <linux/sched/rseq_api.h>
 #include <trace/events/sched.h>
 #undef CREATE_TRACE_POINTS
+#include <trace/events/ipi.h>
 
 #include "sched.h"
 #include "stats.h"
@@ -3753,10 +3754,12 @@ void send_call_function_single_ipi(int cpu)
 {
 	struct rq *rq = cpu_rq(cpu);
 
-	if (!set_nr_if_polling(rq->idle))
+	if (!set_nr_if_polling(rq->idle)) {
+		trace_ipi_send_cpu(_RET_IP_, cpu);
 		arch_send_call_function_single_ipi(cpu);
-	else
+	} else {
 		trace_sched_wake_idle_without_ipi(cpu);
+	}
 }
 
 /*
diff --git a/kernel/smp.c b/kernel/smp.c
index e8cdc025a046..7a7a22d69972 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -26,6 +26,10 @@
 #include <linux/sched/debug.h>
 #include <linux/jump_label.h>
 
+#define CREATE_TRACE_POINTS
+#include <trace/events/ipi.h>
+#undef CREATE_TRACE_POINTS
+
 #include "smpboot.h"
 #include "sched/smp.h"
 
-- 
2.31.1