Re: [PATCH v4 1/4] ethdev: add apis to support access device info

quoted

quoted

+
+int
+rte_eth_dev_set_ringparam(uint8_t port_id, struct rte_dev_ring_info
+*info) {
+	struct rte_eth_dev *dev;
+
+	if (!rte_eth_dev_is_valid_port(port_id)) {
+		PMD_DEBUG_TRACE("Invalid port_id=%d\n", port_id);
+		return -ENODEV;
+	}
+
+	if ((dev= &rte_eth_devices[port_id]) == NULL) {
+		PMD_DEBUG_TRACE("Invalid port device\n");
+		return -ENODEV;
+	}
+
+	FUNC_PTR_OR_ERR_RET(*dev->dev_ops->set_ringparam, -

ENOTSUP);

quoted

+	return (*dev->dev_ops->set_ringparam)(dev, info); }

I am a bit confused, what particular value of rte_dev_ring_info will be
allowed to change?
You can't change number of RXD/TXD at runtime.
You have to stop the device first, and then reconfigure particular queue(s).
Again, you can't reset RXF/TXD without stopping RX/TX first.
So what that function is supposed to do?
As I can see currently, none of the PMD in your patch support it.

Exactly, setting RXD/TXD will require some change on kernel (RX/TX burst) function.
As you already observe that there is no dev_op registered for set_ring.
The API is created as a placeholder for future implementation.
There are a couple of idea thrown around (such as mono- increase/decrease to avoid buffer overrun).
Any suggestion is welcome.

If you don't plan to implement it in current patch-set, then it is better to remove it for now.
About suggestions - as I said, I don't think it is doable without stopping (and reconfiguring) the queue.
Again not sure, why do you want to do that run-tme.
Konstantin