x86/mm: Add tracepoints for TLB flushes

We don't have any good way to figure out what kinds of flushes
are being attempted.  Right now, we can try to use the vm
counters, but those only tell us what we actually did with the
hardware (one-by-one vs full) and don't tell us what was actually
_requested_.

This allows us to select out "interesting" TLB flushes that we
might want to optimize (like the ranged ones) and ignore the ones
that we have very little control over (the ones at context
switch).

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: http://lkml.kernel.org/r/20140731154059.4C96CBA5@viggo.jf.intel.com
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

2 files changed, 48 insertions, 0 deletions

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 96c5750e3110..796deac19fcf 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -516,4 +516,12 @@ struct vm_special_mapping
         struct page **pages;
 };
 
+enum tlb_flush_reason {
+        TLB_FLUSH_ON_TASK_SWITCH,
+        TLB_REMOTE_SHOOTDOWN,
+        TLB_LOCAL_SHOOTDOWN,
+        TLB_LOCAL_MM_SHOOTDOWN,
+        NR_TLB_FLUSH_REASONS,
+};
+
 #endif /* _LINUX_MM_TYPES_H */
diff --git a/include/trace/events/tlb.h b/include/trace/events/tlb.h
new file mode 100644
index 000000000000..13391d288107
--- /dev/null
+++ b/include/trace/events/tlb.h
@@ -0,0 +1,40 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM tlb
+
+#if !defined(_TRACE_TLB_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_TLB_H
+
+#include <linux/mm_types.h>
+#include <linux/tracepoint.h>
+
+#define TLB_FLUSH_REASON        \
+        { 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" }
+
+TRACE_EVENT(tlb_flush,
+
+        TP_PROTO(int reason, unsigned long pages),
+        TP_ARGS(reason, pages),
+
+        TP_STRUCT__entry(
+                __field(          int, reason)
+                __field(unsigned long,  pages)
+        ),
+
+        TP_fast_assign(
+                __entry->reason = reason;
+                __entry->pages  = pages;
+        ),
+
+        TP_printk("pages:%ld reason:%s (%d)",
+                __entry->pages,
+                __print_symbolic(__entry->reason, TLB_FLUSH_REASON),
+                __entry->reason)
+);
+
+#endif /* _TRACE_TLB_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>