hv_balloon: trace post_status

Hyper-V balloon driver makes non-trivial calculations to convert Linux's
representation of free/used memory to what Hyper-V host expects to see. Add
a tracepoint to see what's being sent and where the data comes from.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hv/Makefile

@@ -4,6 +4,7 @@ obj-$(CONFIG_HYPERV_UTILS)	+= hv_utils.o
 obj-$(CONFIG_HYPERV_BALLOON)	+= hv_balloon.o
 
 CFLAGS_hv_trace.o = -I$(src)
+CFLAGS_hv_balloon.o = -I$(src)
 
 hv_vmbus-y := vmbus_drv.o \
 		 hv.o connection.o channel.o \

drivers/hv/hv_balloon.c

@@ -34,6 +34,9 @@
 
 #include <linux/hyperv.h>
 
+#define CREATE_TRACE_POINTS
+#include "hv_trace_balloon.h"
+
 /*
  * We begin with definitions supporting the Dynamic Memory protocol
  * with the host.
@@ -1159,6 +1162,9 @@ static void post_status(struct hv_dynmem_device *dm)
 		 dm->num_pages_added - dm->num_pages_onlined : 0) +
 		compute_balloon_floor();
 
+	trace_balloon_status(status.num_avail, status.num_committed,
+			     vm_memory_committed(), dm->num_pages_ballooned,
+			     dm->num_pages_added, dm->num_pages_onlined);
 	/*
 	 * If our transaction ID is no longer current, just don't
 	 * send the status. This can happen if we were interrupted

drivers/hv/hv_trace_balloon.h

@@ -0,0 +1,48 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM hyperv
+
+#if !defined(_HV_TRACE_BALLOON_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _HV_TRACE_BALLOON_H
+
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(balloon_status,
+	    TP_PROTO(u64 available, u64 committed,
+		     unsigned long vm_memory_committed,
+		     unsigned long pages_ballooned,
+		     unsigned long pages_added,
+		     unsigned long pages_onlined),
+	    TP_ARGS(available, committed, vm_memory_committed,
+		    pages_ballooned, pages_added, pages_onlined),
+	    TP_STRUCT__entry(
+		    __field(u64, available)
+		    __field(u64, committed)
+		    __field(unsigned long, vm_memory_committed)
+		    __field(unsigned long, pages_ballooned)
+		    __field(unsigned long, pages_added)
+		    __field(unsigned long, pages_onlined)
+		    ),
+	    TP_fast_assign(
+		    __entry->available = available;
+		    __entry->committed = committed;
+		    __entry->vm_memory_committed = vm_memory_committed;
+		    __entry->pages_ballooned = pages_ballooned;
+		    __entry->pages_added = pages_added;
+		    __entry->pages_onlined = pages_onlined;
+		    ),
+	    TP_printk("available %lld, committed %lld; vm_memory_committed %ld;"
+		      " pages_ballooned %ld, pages_added %ld, pages_onlined %ld",
+		      __entry->available, __entry->committed,
+		      __entry->vm_memory_committed, __entry->pages_ballooned,
+		      __entry->pages_added, __entry->pages_onlined
+		    )
+	);
+
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH .
+#undef TRACE_INCLUDE_FILE
+#define TRACE_INCLUDE_FILE hv_trace_balloon
+#endif /* _HV_TRACE_BALLOON_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>