Wanlong Gao <gaowanlong@xxxxxxxxxxxxxx> writes: > On 01/02/2013 01:03 PM, Rusty Russell wrote: >> Paolo Bonzini <pbonzini@xxxxxxxxxx> writes: >>> The virtqueue_add_buf function has two limitations: >>> >>> 1) it requires the caller to provide all the buffers in a single call; >>> >>> 2) it does not support chained scatterlists: the buffers must be >>> provided as an array of struct scatterlist; >> >> Chained scatterlists are a horrible interface, but that doesn't mean we >> shouldn't support them if there's a need. >> >> I think I once even had a patch which passed two chained sgs, rather >> than a combo sg and two length numbers. It's very old, but I've pasted >> it below. >> >> Duplicating the implementation by having another interface is pretty >> nasty; I think I'd prefer the chained scatterlists, if that's optimal >> for you. > > I rebased against virtio-next and use it in virtio-scsi, and tested it with 4 targets > virtio-scsi devices and host cpu idle=poll. Saw a little performance regression here. Sure, but now you should be able to eliminate virtscsi_map_sgl(), right? You should be able to use scsi_out(sc) and scsi_in(sc) directly, which is what Paulo wanted to do... Right Paulo? Thanks, Rusty. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
