RE: [PATCH v4] Drivers: hv: vmbus: Expose counters for interrupts and full conditions

[Michael Kelley]

From: Kimberly Brown <kimbrownkd@xxxxxxxxx> Sent: Sunday, February 3, 2019 11:13 PM
> 
> 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@xxxxxxxxx>
> ---
> 
Reviewed-by:  Michael Kelley <mikelley@xxxxxxxxxxxxx>