Hi Rusty, On Thu, 2008-12-18 at 17:10 +0000, Mark McLoughlin wrote: > Add a new feature flag for indirect ring entries. These are ring > entries which point to a table of buffer descriptors. > > The idea here is to increase the ring capacity by allowing a larger > effective ring size whereby the ring size dictates the number of > requests that may be outstanding, rather than the size of those > requests. > > This should be most effective in the case of block I/O where we can > potentially benefit by concurrently dispatching a large number of > large requests. Even in the simple case of single segment block > requests, this results in a threefold increase in ring capacity. Apparently, this would also be useful for the windows virtio-net drivers. Dor can explain further, but apparently Windows has been observed passing the driver a packet with >256 fragments when using TSO. With a ring size of 256, the guest can either drop the packet or copy it into a single buffer. We'd much rather if we could use an indirect ring entry to pass this number of fragments without copying. For reference the original patch was here: http://lkml.org/lkml/2008/12/18/212 Cheers, Mark. _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/virtualization
