>>>>> "Jeff" == Jeff Garzik <jgarzik@xxxxxxxxxxxxxxxx> writes:
Jeff> 1) Rx Skb recycling. It would be nice to have skbs returned to
Jeff> the driver after the net core is done with them, rather than
Jeff> have netif_rx free the skb. Many drivers pre-allocate a number
Jeff> of maximum-sized skbs into which the net card DMA's data. If
Jeff> netif_rx returned the SKB instead of freeing it, the driver
Jeff> could simply flip the DescriptorOwned bit for that buffer,
Jeff> giving it immediately back to the net card.
Jeff> Advantages: A de-allocation immediately followed by a
Jeff> reallocation is eliminated, less L1 cache pollution during
Jeff> interrupt handling. Potentially less DMA traffic between card
Jeff> and host.
Jeff> Disadvantages?
I already tried this with the AceNIC GigE driver some time ago, and
after Ingo came up with a per-CPU slab patch the gain was gone. I am
not sure the complexity is worth it.
Jes
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