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 <[email protected]>
Reviewed-by: Michael Kelley <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index d5678a0..64698ec 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -751,6 +751,19 @@ struct vmbus_channel {
u64 interrupts; /* Host to Guest interrupts */
u64 sig_events; /* Guest to Host events */
+ /*
+ * Guest to host interrupts caused by the outbound ring buffer changing
+ * from empty to not empty.
+ */
+ u64 intr_out_empty;
+
+ /*
+ * Indicates that a full outbound ring buffer was encountered. The flag
+ * is set to true when a full outbound ring buffer is encountered and
+ * set to false when a write to the outbound ring buffer is completed.
+ */
+ bool out_full_flag;
+
/* Channel callback's invoked in softirq context */
struct tasklet_struct callback_event;
void (*onchannel_callback)(void *context);
@@ -903,6 +916,24 @@ struct vmbus_channel {
* vmbus_connection.work_queue and hang: see vmbus_process_offer().
*/
struct work_struct add_channel_work;
+
+ /*
+ * Guest to host interrupts caused by the inbound ring buffer changing
+ * from full to not full while a packet is waiting.
+ */
+ u64 intr_in_full;
+
+ /*
+ * The total number of write operations that encountered a full
+ * outbound ring buffer.
+ */
+ u64 out_full_total;
+
+ /*
+ * The number of write operations that were the first to encounter a
+ * full outbound ring buffer.
+ */
+ u64 out_full_first;
};
static inline bool is_hvsock_channel(const struct vmbus_channel *c)
@@ -936,6 +967,21 @@ static inline void *get_per_channel_state(struct vmbus_channel *c)
static inline void set_channel_pending_send_size(struct vmbus_channel *c,
u32 size)
{
+ unsigned long flags;
+
+ if (size) {
+ spin_lock_irqsave(&c->outbound.ring_lock, flags);
+ ++c->out_full_total;
+
+ if (!c->out_full_flag) {
+ ++c->out_full_first;
+ c->out_full_flag = true;
+ }
+ spin_unlock_irqrestore(&c->outbound.ring_lock, flags);
+ } else {
+ c->out_full_flag = false;
+ }
+
c->outbound.ring_buffer->pending_send_sz = size;
}
