similar to: [PATCH AUTOSEL 4.4 33/53] vhost_net: disable zerocopy by default

From: Jason Wang <jasowang at redhat.com> [ Upstream commit 098eadce3c622c07b328d0a43dda379b38cf7c5e ] Vhost_net was known to suffer from HOL[1] issues which is not easy to fix. Several downstream disable the feature by default. What's more, the datapath was split and datacopy path got the support of batching and XDP support recently which makes it faster than zerocopy part for small

From: Jason Wang <jasowang at redhat.com> [ Upstream commit 098eadce3c622c07b328d0a43dda379b38cf7c5e ] Vhost_net was known to suffer from HOL[1] issues which is not easy to fix. Several downstream disable the feature by default. What's more, the datapath was split and datacopy path got the support of batching and XDP support recently which makes it faster than zerocopy part for small

From: Jason Wang <jasowang at redhat.com> [ Upstream commit 098eadce3c622c07b328d0a43dda379b38cf7c5e ] Vhost_net was known to suffer from HOL[1] issues which is not easy to fix. Several downstream disable the feature by default. What's more, the datapath was split and datacopy path got the support of batching and XDP support recently which makes it faster than zerocopy part for small

From: Jason Wang <jasowang at redhat.com> [ Upstream commit 098eadce3c622c07b328d0a43dda379b38cf7c5e ] Vhost_net was known to suffer from HOL[1] issues which is not easy to fix. Several downstream disable the feature by default. What's more, the datapath was split and datacopy path got the support of batching and XDP support recently which makes it faster than zerocopy part for small

From: Jason Wang <jasowang at redhat.com> [ Upstream commit 098eadce3c622c07b328d0a43dda379b38cf7c5e ] Vhost_net was known to suffer from HOL[1] issues which is not easy to fix. Several downstream disable the feature by default. What's more, the datapath was split and datacopy path got the support of batching and XDP support recently which makes it faster than zerocopy part for small

Vhost_net was known to suffer from HOL[1] issues which is not easy to fix. Several downstream disable the feature by default. What's more, the datapath was split and datacopy path got the support of batching and XDP support recently which makes it faster than zerocopy part for small packets transmission. It looks to me that disable zerocopy by default is more appropriate. It cold be enabled

On 2017?09?02? 00:17, Willem de Bruijn wrote: >>>> This is not a 50/50 split, which impliesTw that some packets from the >>>> large >>>> packet flow are still converted to copying. Without the change the rate >>>> without queue was 80k zerocopy vs 80k copy, so this choice of >>>> (vq->num >> 2) appears too conservative.

On Fri, Nov 23, 2018 at 11:00:15AM +0800, Jason Wang wrote: > This makes vhost_net to support in order feature. This is as simple as > use datacopy path when it was negotiated. An alternative is not to > advertise in order when zerocopy is enabled which tends to be > suboptimal consider zerocopy may suffer from e.g HOL issues. Well IIRC vhost_zerocopy_signal_used is used to actually

On Mon, Sep 4, 2017 at 5:03 AM, Jason Wang <jasowang at redhat.com> wrote: > > > On 2017?09?02? 00:17, Willem de Bruijn wrote: >>>>> >>>>> This is not a 50/50 split, which impliesTw that some packets from the >>>>> large >>>>> packet flow are still converted to copying. Without the change the rate >>>>>

On Mon, Sep 4, 2017 at 5:03 AM, Jason Wang <jasowang at redhat.com> wrote: > > > On 2017?09?02? 00:17, Willem de Bruijn wrote: >>>>> >>>>> This is not a 50/50 split, which impliesTw that some packets from the >>>>> large >>>>> packet flow are still converted to copying. Without the change the rate >>>>>

This makes vhost_net to support in order feature. This is as simple as use datacopy path when it was negotiated. An alternative is not to advertise in order when zerocopy is enabled which tends to be suboptimal consider zerocopy may suffer from e.g HOL issues. Signed-off-by: Jason Wang <jasowang at redhat.com> --- drivers/vhost/net.c | 6 ++++-- 1 file changed, 4 insertions(+), 2

>>> This is not a 50/50 split, which impliesTw that some packets from the >>> large >>> packet flow are still converted to copying. Without the change the rate >>> without queue was 80k zerocopy vs 80k copy, so this choice of >>> (vq->num >> 2) appears too conservative. >>> >>> However, testing with (vq->num >> 1) was

>>> This is not a 50/50 split, which impliesTw that some packets from the >>> large >>> packet flow are still converted to copying. Without the change the rate >>> without queue was 80k zerocopy vs 80k copy, so this choice of >>> (vq->num >> 2) appears too conservative. >>> >>> However, testing with (vq->num >> 1) was

Instead of mixing zerocopy and datacopy logics, this patch tries to split datacopy logic out. This results for a more compact code and specific optimization could be done on top more easily. Signed-off-by: Jason Wang <jasowang at redhat.com> --- drivers/vhost/net.c | 111 +++++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 102 insertions(+), 9 deletions(-) diff --git

On Thu, Aug 31, 2017 at 11:25 PM, Jason Wang <jasowang at redhat.com> wrote: > > > On 2017?08?31? 22:30, Willem de Bruijn wrote: >>> >>> Incomplete results at this stage, but I do see this correlation between >>> flows. It occurs even while not running out of zerocopy descriptors, >>> which I cannot yet explain. >>> >>> Running

On Mon, 21 May 2018 17:04:25 +0800 Jason wrote: > Instead of mixing zerocopy and datacopy logics, this patch tries to > split datacopy logic out. This results for a more compact code and > specific optimization could be done on top more easily. > > Signed-off-by: Jason Wang <jasowang at redhat.com> > --- > drivers/vhost/net.c | 111

On Fri, Aug 16, 2013 at 01:16:30PM +0800, Jason Wang wrote: > We used to limit the max pending DMAs to prevent guest from pinning too many > pages. But this could be removed since: > > - We have the sk_wmem_alloc check in both tun/macvtap to do the same work > - This max pending check were almost useless since it was one done when there's > no new buffers coming from

On Fri, Aug 16, 2013 at 01:16:30PM +0800, Jason Wang wrote: > We used to limit the max pending DMAs to prevent guest from pinning too many > pages. But this could be removed since: > > - We have the sk_wmem_alloc check in both tun/macvtap to do the same work > - This max pending check were almost useless since it was one done when there's > no new buffers coming from

We used to limit the max pending DMAs to prevent guest from pinning too many pages. But this could be removed since: - We have the sk_wmem_alloc check in both tun/macvtap to do the same work - This max pending check were almost useless since it was one done when there's no new buffers coming from guest. Guest can easily exceeds the limitation. - We've already check upend_idx != done_idx

On 08/16/2013 06:02 PM, Michael S. Tsirkin wrote: > On Fri, Aug 16, 2013 at 01:16:30PM +0800, Jason Wang wrote: >> We used to limit the max pending DMAs to prevent guest from pinning too many >> pages. But this could be removed since: >> >> - We have the sk_wmem_alloc check in both tun/macvtap to do the same work >> - This max pending check were almost useless