From: David S. Miller Date: Mon, 25 Aug 2014 06:02:53 +0000 (-0700) Subject: Merge branch 'ndo_xmit_flush' X-Git-Tag: firefly_0821_release~176^2~3043^2~232 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=fe88e6dd8b9ac65912d0d9d9372fe421d6eeb21e;p=firefly-linux-kernel-4.4.55.git Merge branch 'ndo_xmit_flush' Basic deferred TX queue flushing infrastructure. Over time, and specifically and more recently at the Networking Workshop during Kernel SUmmit in Chicago, we have discussed the idea of having some way to optimize transmits of multiple TX packets at a time. There are several areas of overhead that could be amortized with such schemes. One has to do with locking and transactional overhead, the other has to do with device specific costs. This patch set here is more aimed at device specific costs. Typically a device queues up a packet in the TX queue and then has to do something to have the device start processing that new entry. Sometimes this is composed of doing an MMIO write to a "tail" register, and in other cases it can involve something as expensive as a hypervisor call. The basic setup defined here is that when the driver supports deferred TX queue flushing, ndo_start_xmit should no longer perform that operation. Instead a new operation, ndo_xmit_flush, should do it. I have converted IGB and virtio_net as example initial users. The IGB conversion is tested, virtio_net is not but it does compile :-) All ndo_start_xmit call sites have been abstracted behind a new helper called netdev_start_xmit(). This just adds the infrastructure, it does not actually add any instances of actually doing multiple ndo_start_xmit calls per ndo_xmit_flush invocation. Signed-off-by: David S. Miller --- fe88e6dd8b9ac65912d0d9d9372fe421d6eeb21e