On Thu, Dec 03, 2009 at 04:17:43PM +0100, Eric Dumazet wrote:

Jarek Poplawski a écrit :

quoted

Take 2 (with forgotten headers, sorry).

Very nice, thanks !

quoted

Here is a proposal of netdev api change. I hope Michael finds time
to try if this can be really useful for drivers.

Thanks,
Jarek P.
---------------> (take 2)

This patch separates allocation of TX subqueues from alloc_netdev_mq()
to realloc_netdev_mq() to allow for resizing like in this example:

some_nic_probe()
{
	...
	dev = alloc_etherdev_mq(sizeof(*bp), 1)
	...
	if (MSI-X_available && device_supports_MSI-X_and_multiqueue)
		realloc_netdev_mq(dev, TX_MAX_RINGS)
	register_netdev(dev)
	...
}

Or the reverse :

ie, the device first allocate its max possible tx rings

dev = alloc_etherdev_mq(sizeof(*bp), 128)

then, later, try to reduce it, when knowing exact tx count.

Right, especially when we know it's a common config/capability for
a NIC.

if (realloc_netdev_mq(dev, real_queues))
	dev->real_num_tx_queues = real_queues;

In this case the memory error is not fatal.

Good point! We can consider doing this inside the function too?

Thanks,
Jarek P.