From: "Michael S. Tsirkin" <mst@redhat•com>
To: Marcelo Ricardo Leitner <marcelo.leitner@gmail•com>
Cc: Vlad Yasevich <vyasevic@redhat•com>,
Vladislav Yasevich <vyasevich@gmail•com>,
netdev@vger•kernel.org, linux-sctp@vger•kernel.org,
virtualization@lists•linux-foundation.org, jasowang@redhat•com,
nhorman@tuxdriver•com
Subject: Re: [PATCH net-next 0/5] virtio-net: Add SCTP checksum offload support
Date: Fri, 20 Apr 2018 21:32:24 +0300 [thread overview]
Message-ID: <20180420213118-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <20180420172219.GR4716@localhost.localdomain>
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
> > > >
next prev parent reply other threads:[~2018-04-20 18:32 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-02 13:40 [PATCH net-next 0/5] virtio-net: Add SCTP checksum offload support Vladislav Yasevich
2018-04-02 13:40 ` [PATCH net-next 1/5] virtio: Add support for SCTP checksum offloading Vladislav Yasevich
2018-04-10 3:17 ` Jason Wang
2018-04-11 22:39 ` Marcelo Ricardo Leitner
2018-04-11 22:49 ` Michael S. Tsirkin
2018-04-16 13:45 ` Vlad Yasevich
2018-04-16 15:52 ` Michael S. Tsirkin
2018-04-16 17:09 ` Michael S. Tsirkin
2018-04-17 19:06 ` Vlad Yasevich
2018-04-16 17:07 ` Michael S. Tsirkin
2018-04-02 13:40 ` [PATCH net-next 2/5] sctp: Handle sctp packets with CHECKSUM_PARTIAL Vladislav Yasevich
2018-04-02 13:40 ` [PATCH net-next 3/5] sctp: Build sctp offload support into the base kernel Vladislav Yasevich
2018-04-02 13:40 ` [PATCH net-next 4/5] tun: Add support for SCTP checksum offload Vladislav Yasevich
2018-04-03 0:49 ` kbuild test robot
2018-04-16 17:12 ` Michael S. Tsirkin
2018-04-02 13:40 ` [PATCH net-next 5/5] macvlan/macvtap: " Vladislav Yasevich
2018-04-04 15:31 ` Davide Caratti
2018-04-16 17:14 ` Michael S. Tsirkin
2018-04-02 14:16 ` [PATCH net-next 0/5] virtio-net: Add SCTP checksum offload support David Miller
2018-04-02 14:47 ` Marcelo Ricardo Leitner
2018-04-17 20:35 ` Vlad Yasevich
2018-04-18 1:33 ` Marcelo Ricardo Leitner
2018-04-18 6:57 ` Xin Long
2018-04-18 14:06 ` Michael S. Tsirkin
2018-04-20 17:22 ` Marcelo Ricardo Leitner
2018-04-20 18:32 ` Michael S. Tsirkin [this message]
2018-04-23 13:17 ` Vlad Yasevich
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