On Fri, Apr 20, 2018 at 02:22:19PM -0300, Marcelo Ricardo Leitner wrote: > On Wed, Apr 18, 2018 at 05:06:46PM +0300, Michael S. Tsirkin wrote: > > On Tue, Apr 17, 2018 at 04:35:18PM -0400, Vlad Yasevich wrote: > > > On 04/02/2018 10:47 AM, Marcelo Ricardo Leitner wrote: > > > > On Mon, Apr 02, 2018 at 09:40:01AM -0400, Vladislav Yasevich wrote: > > > >> Now that we have SCTP offload capabilities in the kernel, we can add > > > >> them to virtio as well. First step is SCTP checksum. > > > > > > > > Thanks. > > > > > > > >> As for GSO, the way sctp GSO is currently implemented buys us nothing > > > >> in added support to virtio. To add true GSO, would require a lot of > > > >> re-work inside of SCTP and would require extensions to the virtio > > > >> net header to carry extra sctp data. > > > > > > > > Can you please elaborate more on this? Is this because SCTP GSO relies > > > > on the gso skb format for knowing how to segment it instead of having > > > > a list of sizes? > > > > > > > > > > it's mainly because all the true segmentation, placing data into chunks, > > > has already happened. All that GSO does is allow for higher bundling > > > rate between VMs. If that is all SCTP GSO ever going to do, that fine, > > > but the goal is to do real GSO eventually and potentially reduce the > > > amount of memory copying we are doing. > > > If we do that, any current attempt at GSO in virtio would have to be > > > depricated and we'd need GSO2 or something like that. > > > > Batching helps virtualization *a lot* though. > > Yep. The results posted by Xin in the other email give good insights > on it. > > > Are there actual plans for GSO2? Is it just for SCTP? > > No plans. In this context, at least, yes, just for SCTP. > > It was a supposition in case we start doing a different GSO for SCTP, > one more like what we have for TCP. > > Currently, as the SCTP GSO code doesn't leave the system, we can > update it if we want. But by the moment we add support for it in > virtio, we will have to be backwards compatible if we end up doing > SCTP GSO differently. At least for TX you can always just disable the optimization. Won't be worse than what is there now. RX is trickier - but that's GRO not GSO. > But again, I don't think such approach for SCTP GSO would be neither > feasible or worth. The complexity for it, to work across stream > schedules and late TSN allocation, would do more harm then good IMO. > > > > > > > > > This is why, after doing the GSO support, I decided not to include it. > > > > > > -vlad > > > > Marcelo > > > > -- To unsubscribe from this list: send the line "unsubscribe linux-sctp" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
