[PATCH requirements 4/7] net-features: Add notification coalescing requirements

[Parav Pandit <parav@nvidia.com>]

Add virtio net device notification coalescing improvements requirements.

Signed-off-by: Parav Pandit <parav@nvidia.com>
---
changelog:
v1->v2:
- addressed comments from Stefan
- redrafted the requirements to use rearm term and avoid queue enable
  confusion
v0->v1:
- updated the description
---
 net-workstream/features-1.4.md | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/net-workstream/features-1.4.md b/net-workstream/features-1.4.md
index e04727a..27a7886 100644
--- a/net-workstream/features-1.4.md
+++ b/net-workstream/features-1.4.md
@@ -8,6 +8,7 @@ together is desired while updating the virtio net interface.
 # 2. Summary
 1. Device counters visible to the driver
 2. Low latency tx and rx virtqueues for PCI transport
+3. Virtqueue notification coalescing re-arming support
 
 # 3. Requirements
 ## 3.1 Device counters
@@ -164,3 +165,13 @@ struct vnet_rx_completion {
    which can be recycled by the driver when the packets from the completed
    page is fully consumed.
 8. The device should be able to consume multiple pages for a receive GSO stream.
+
+## 3.3 Virtqueue notification coalescing re-arming support
+0. Design goal:
+   a. Avoid constant notifications from the device even in conditions when
+      the driver may not have acted on the previous pending notification.
+1. When Tx and Rx virtqueue notification coalescing is enabled, and when such
+   a notification is reported by the device, the device stops sending further
+   notifications until the driver rearms the notifications of the virtqueue.
+2. When the driver rearms the notification of the virtqueue, the device
+   to notify again if notification coalescing conditions are met.
-- 
2.26.2