Drivers: hv: vmbus: Expose per-channel interrupts and events counters

When investigating performance, it is useful to be able to look at
the number of host and guest events per-channel. This is equivalent
to per-device interrupt statistics.
Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/ABI/stable/sysfs-bus-vmbus

@@ -61,39 +61,53 @@ Date:		September. 2017
 KernelVersion:	4.14
 Contact:	Stephen Hemminger <sthemmin@microsoft.com>
 Description:	Inbound channel signaling state
-Users:		Debuggig tools
+Users:		Debugging tools
 
 What:		/sys/bus/vmbus/devices/vmbus_*/channels/relid/latency
 Date:		September. 2017
 KernelVersion:	4.14
 Contact:	Stephen Hemminger <sthemmin@microsoft.com>
 Description:	Channel signaling latency
-Users:		Debuggig tools
+Users:		Debugging tools
 
 What:		/sys/bus/vmbus/devices/vmbus_*/channels/relid/out_mask
 Date:		September. 2017
 KernelVersion:	4.14
 Contact:	Stephen Hemminger <sthemmin@microsoft.com>
 Description:	Outbound channel signaling state
-Users:		Debuggig tools
+Users:		Debugging tools
 
 What:		/sys/bus/vmbus/devices/vmbus_*/channels/relid/pending
 Date:		September. 2017
 KernelVersion:	4.14
 Contact:	Stephen Hemminger <sthemmin@microsoft.com>
 Description:	Channel interrupt pending state
-Users:		Debuggig tools
+Users:		Debugging tools
 
 What:		/sys/bus/vmbus/devices/vmbus_*/channels/relid/read_avail
 Date:		September. 2017
 KernelVersion:	4.14
 Contact:	Stephen Hemminger <sthemmin@microsoft.com>
 Description:	Bytes availabble to read
-Users:		Debuggig tools
+Users:		Debugging tools
 
 What:		/sys/bus/vmbus/devices/vmbus_*/channels/relid/write_avail
 Date:		September. 2017
 KernelVersion:	4.14
 Contact:	Stephen Hemminger <sthemmin@microsoft.com>
 Description:	Bytes availabble to write
-Users:		Debuggig tools
+Users:		Debugging tools
+
+What:		/sys/bus/vmbus/devices/vmbus_*/channels/relid/events
+Date:		September. 2017
+KernelVersion:	4.14
+Contact:	Stephen Hemminger <sthemmin@microsoft.com>
+Description:	Number of times we have signaled the host
+Users:		Debugging tools
+
+What:		/sys/bus/vmbus/devices/vmbus_*/channels/relid/interrupts
+Date:		September. 2017
+KernelVersion:	4.14
+Contact:	Stephen Hemminger <sthemmin@microsoft.com>
+Description:	Number of times we have taken an interrupt (incoming)
+Users:		Debugging tools

drivers/hv/connection.c

@@ -409,6 +409,8 @@ void vmbus_set_event(struct vmbus_channel *channel)
 	if (!channel->is_dedicated_interrupt)
 		vmbus_send_interrupt(child_relid);
 
+	++channel->sig_events;
+
 	hv_do_fast_hypercall8(HVCALL_SIGNAL_EVENT, channel->sig_event);
 }
 EXPORT_SYMBOL_GPL(vmbus_set_event);

drivers/hv/vmbus_drv.c

@@ -944,6 +944,8 @@ static void vmbus_chan_sched(struct hv_per_cpu_context *hv_cpu)
 			if (channel->rescind)
 				continue;
 
+			++channel->interrupts;
+
 			switch (channel->callback_mode) {
 			case HV_CALL_ISR:
 				vmbus_channel_isr(channel);
@@ -1237,6 +1239,18 @@ static ssize_t channel_latency_show(const struct vmbus_channel *channel,
 }
 VMBUS_CHAN_ATTR(latency, S_IRUGO, channel_latency_show, NULL);
 
+static ssize_t channel_interrupts_show(const struct vmbus_channel *channel, char *buf)
+{
+	return sprintf(buf, "%llu\n", channel->interrupts);
+}
+VMBUS_CHAN_ATTR(interrupts, S_IRUGO, channel_interrupts_show, NULL);
+
+static ssize_t channel_events_show(const struct vmbus_channel *channel, char *buf)
+{
+	return sprintf(buf, "%llu\n", channel->sig_events);
+}
+VMBUS_CHAN_ATTR(events, S_IRUGO, channel_events_show, NULL);
+
 static struct attribute *vmbus_chan_attrs[] = {
 	&chan_attr_out_mask.attr,
 	&chan_attr_in_mask.attr,
@@ -1245,6 +1259,8 @@ static struct attribute *vmbus_chan_attrs[] = {
 	&chan_attr_cpu.attr,
 	&chan_attr_pending.attr,
 	&chan_attr_latency.attr,
+	&chan_attr_interrupts.attr,
+	&chan_attr_events.attr,
 	NULL
 };
 

include/linux/hyperv.h

@@ -719,6 +719,10 @@ struct vmbus_channel {
 
 	struct vmbus_close_msg close_msg;
 
+	/* Statistics */
+	u64	interrupts;	/* Host to Guest interrupts */
+	u64	sig_events;	/* Guest to Host events */
+
 	/* Channel callback's invoked in softirq context */
 	struct tasklet_struct callback_event;
 	void (*onchannel_callback)(void *context);