Drivers: hv: vmbus: Expose counters for interrupts and full conditions

Counter values for per-channel interrupts and ring buffer full
conditions are useful for investigating performance.

Expose counters in sysfs for 2 types of guest to host interrupts:
1) Interrupts caused by the channel's outbound ring buffer transitioning
from empty to not empty
2) Interrupts caused by the channel's inbound ring buffer transitioning
from full to not full while a packet is waiting for enough buffer space to
become available

Expose 2 counters in sysfs for the number of times that write operations
encountered a full outbound ring buffer:
1) The total number of write operations that encountered a full
condition
2) The number of write operations that were the first to encounter a
full condition

Increment the outbound full condition counters in the
hv_ringbuffer_write() function because, for most drivers, a full
outbound ring buffer is detected in that function. Also increment the
outbound full condition counters in the set_channel_pending_send_size()
function. In the hv_sock driver, a full outbound ring buffer is detected
and set_channel_pending_send_size() is called before
hv_ringbuffer_write() is called.

I tested this patch by confirming that the sysfs files were created and
observing the counter values. The values seemed to increase by a
reasonable amount when the Hyper-v related drivers were in use.

Signed-off-by: Kimberly Brown <kimbrownkd@gmail.com>
Reviewed-by:  Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

1 files changed, 36 insertions, 0 deletions

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 126c2de39e35..1264b17e7e9d 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -1484,6 +1484,38 @@ static ssize_t channel_events_show(const struct vmbus_channel *channel, char *bu
 }
 static VMBUS_CHAN_ATTR(events, S_IRUGO, channel_events_show, NULL);
 
+static ssize_t channel_intr_in_full_show(const struct vmbus_channel *channel,
+					 char *buf)
+{
+	return sprintf(buf, "%llu\n",
+		       (unsigned long long)channel->intr_in_full);
+}
+static VMBUS_CHAN_ATTR(intr_in_full, 0444, channel_intr_in_full_show, NULL);
+
+static ssize_t channel_intr_out_empty_show(const struct vmbus_channel *channel,
+					   char *buf)
+{
+	return sprintf(buf, "%llu\n",
+		       (unsigned long long)channel->intr_out_empty);
+}
+static VMBUS_CHAN_ATTR(intr_out_empty, 0444, channel_intr_out_empty_show, NULL);
+
+static ssize_t channel_out_full_first_show(const struct vmbus_channel *channel,
+					   char *buf)
+{
+	return sprintf(buf, "%llu\n",
+		       (unsigned long long)channel->out_full_first);
+}
+static VMBUS_CHAN_ATTR(out_full_first, 0444, channel_out_full_first_show, NULL);
+
+static ssize_t channel_out_full_total_show(const struct vmbus_channel *channel,
+					   char *buf)
+{
+	return sprintf(buf, "%llu\n",
+		       (unsigned long long)channel->out_full_total);
+}
+static VMBUS_CHAN_ATTR(out_full_total, 0444, channel_out_full_total_show, NULL);
+
 static ssize_t subchannel_monitor_id_show(const struct vmbus_channel *channel,
 					  char *buf)
 {
@@ -1509,6 +1541,10 @@ static struct attribute *vmbus_chan_attrs[] = {
 	&chan_attr_latency.attr,
 	&chan_attr_interrupts.attr,
 	&chan_attr_events.attr,
+	&chan_attr_intr_in_full.attr,
+	&chan_attr_intr_out_empty.attr,
+	&chan_attr_out_full_first.attr,
+	&chan_attr_out_full_total.attr,
 	&chan_attr_monitor_id.attr,
 	&chan_attr_subchannel_id.attr,
 	NULL