Commit 10595902 authored Jan 12, 2015 by Pankaj Gupta Committed by David S. Miller Jan 12, 2015

net: allow large number of rx queues



netif_alloc_rx_queues() uses kcalloc() to allocate memory
for "struct netdev_queue *_rx" array.
If we are doing large rx queue allocation kcalloc() might
fail, so this patch does a fallback to vzalloc().
Similar implementation is done for tx queue allocation in
netif_alloc_netdev_queues().

We avoid failure of high order memory allocation
with the help of vzalloc(), this allows us to do large
rx and tx queue allocation which in turn helps us to
increase the number of queues in tun.

As vmalloc() adds overhead on a critical network path,
__GFP_REPEAT flag is used with kzalloc() to do this fallback
only when really needed.

Signed-off-by: Pankaj Gupta <pagupta@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: David Gibson <dgibson@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent e350a96e

net/core/dev.c

+8 −5

Original line number	Diff line number	Diff line
		@@ -6172,13 +6172,16 @@ static int netif_alloc_rx_queues(struct net_device *dev)
		{
		unsigned int i, count = dev->num_rx_queues;
		struct netdev_rx_queue *rx;
		size_t sz = count * sizeof(*rx);

		BUG_ON(count < 1);

		rx = kcalloc(count, sizeof(struct netdev_rx_queue), GFP_KERNEL);
		rx = kzalloc(sz, GFP_KERNEL \| __GFP_NOWARN \| __GFP_REPEAT);
		if (!rx) {
		rx = vzalloc(sz);
		if (!rx)
		return -ENOMEM;

		}
		dev->_rx = rx;

		for (i = 0; i < count; i++)
		@@ -6808,7 +6811,7 @@ void free_netdev(struct net_device *dev)

		netif_free_tx_queues(dev);
		#ifdef CONFIG_SYSFS
		kfree(dev->_rx);
		kvfree(dev->_rx);
		#endif

		kfree(rcu_dereference_protected(dev->ingress_queue, 1));

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