Re: [Xen-devel] ring buffer overflow

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Fri, 2011-09-30 at 05:18 +0100, David Xu wrote:
> Hi,
> 
> Does anybody know whether the ring buffer between front end and back
> end will suffer from overflow? I just wonder if the ring buffer will
> be full and drop some packets when the Net I/O load is very heavy.

In the case of networking whichever end is putting stuff on the ring
checks that there is enough room and will stop the queue when it cannot
transmit any more and restart when room becomes available.

> BTW, If I want to change the size of i/o ring buffer, how should I do?
> I tried to reset the NET_TX_RING_SIZE and NET_RX_RING_SIZE in both
> front end and back end, but it seems doesn't work. Thanks.

Currently the rings are limited to 1 page so if you want to increase the
size you would need to add multipage ring support to the network
protocol. There have been patches to do this for the blk protocol but I
do not recall any for the net protocol.

Ian.



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