[PATCH 1/4] x86, mm: Trace when an IPI is about to be sent

[Mel Gorman]

It is easy to trace when an IPI is received to flush a TLB but harder to
detect what event sent it. This patch makes it easy to identify the source
of IPIs being transmitted for TLB flushes on x86.

Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
---
 arch/x86/mm/tlb.c          | 1 +
 include/linux/mm_types.h   | 1 +
 include/trace/events/tlb.h | 3 ++-
 3 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 3250f2371aea..2da824c1c140 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -140,6 +140,7 @@ void native_flush_tlb_others(const struct cpumask *cpumask,
 	info.flush_end = end;
 
 	count_vm_tlb_event(NR_TLB_REMOTE_FLUSH);
+	trace_tlb_flush(TLB_REMOTE_SEND_IPI, end - start);
 	if (is_uv_system()) {
 		unsigned int cpu;
 
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 199a03aab8dc..856038aa166e 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -532,6 +532,7 @@ enum tlb_flush_reason {
 	TLB_REMOTE_SHOOTDOWN,
 	TLB_LOCAL_SHOOTDOWN,
 	TLB_LOCAL_MM_SHOOTDOWN,
+	TLB_REMOTE_SEND_IPI,
 	NR_TLB_FLUSH_REASONS,
 };
 
diff --git a/include/trace/events/tlb.h b/include/trace/events/tlb.h
index 0e7635765153..0fc101472988 100644
--- a/include/trace/events/tlb.h
+++ b/include/trace/events/tlb.h
@@ -11,7 +11,8 @@
 	{ TLB_FLUSH_ON_TASK_SWITCH,	"flush on task switch" },	\
 	{ TLB_REMOTE_SHOOTDOWN,		"remote shootdown" },		\
 	{ TLB_LOCAL_SHOOTDOWN,		"local shootdown" },		\
-	{ TLB_LOCAL_MM_SHOOTDOWN,	"local mm shootdown" }
+	{ TLB_LOCAL_MM_SHOOTDOWN,	"local mm shootdown" },		\
+	{ TLB_REMOTE_SEND_IPI,		"remote ipi send" }
 
 TRACE_EVENT_CONDITION(tlb_flush,
 
-- 
2.1.2

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