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

Mel Gorman
2015-06-09T17:32:19Z

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@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Dave Hansen <dave.hansen@intel.com>
---
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 8d37e26a1007..86ad9f902042 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -534,6 +534,7 @@ 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 4250f364a6ca..bc8815f45f3b 100644
--- a/include/trace/events/tlb.h
+++ b/include/trace/events/tlb.h
@@ -11,7 +11,8 @@
EM( TLB_FLUSH_ON_TASK_SWITCH, "flush on task switch" ) \
EM( TLB_REMOTE_SHOOTDOWN, "remote shootdown" ) \
EM( TLB_LOCAL_SHOOTDOWN, "local shootdown" ) \
- EMe( TLB_LOCAL_MM_SHOOTDOWN, "local mm shootdown" )
+ EM( TLB_LOCAL_MM_SHOOTDOWN, "local mm shootdown" ) \
+ EMe( TLB_REMOTE_SEND_IPI, "remote ipi send" )

/*
* First define the enums in TLB_FLUSH_REASON to be exported to userspace
--
2.3.5