[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] [PATCH net RFC] xen-netback: Fix grant ref resolution in RX path

On 15/05/14 09:31, Ian Campbell wrote:
On Wed, 2014-05-14 at 12:12 +0100, Zoltan Kiss wrote:
The 'cleanup' of stale ubufs should be right after __pskb_pull_tail().
We can't fix every place in the kernel where frags might be changed,
especially with a netback specific stuff, so unfortunately that won't work

Is it worth fixing up the ones in netback though so that the things
injected into the stack are consistent when we hand them over? It would
avoid some search overhead on the rx path at the other end I guess?
Perhaps not significant though.

There are plans to remove that unconditional pull, as it damages performance. It is better to use during checksum setup maybe_pull_tail, and pull up whatever is needed for checksum setup (this is already done, partially). A sensible netfront would send the header in the first slot anyway, so netback won't pull, and it definitely won't pull the whole first frag.



Xen-devel mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.