On 2017年02月06日 12:39, Michael S. Tsirkin wrote:
On Sun, Feb 05, 2017 at 05:36:34PM -0500, David Miller wrote:
From: John Fastabend <john.fastab...@gmail.com>
Date: Thu, 02 Feb 2017 19:14:05 -0800
This series adds adjust head support for virtio. The following is my
test setup. I use qemu + virtio as follows,
./x86_64-softmmu/qemu-system-x86_64 \
-hda /var/lib/libvirt/images/Fedora-test0.img \
-m 4096 -enable-kvm -smp 2 -netdev tap,id=hn0,queues=4,vhost=on \
-device
virtio-net-pci,netdev=hn0,mq=on,guest_tso4=off,guest_tso6=off,guest_ecn=off,guest_ufo=off,vectors=9
In order to use XDP with virtio until LRO is supported TSO must be
turned off in the host. The important fields in the above command line
are the following,
guest_tso4=off,guest_tso6=off,guest_ecn=off,guest_ufo=off
Also note it is possible to conusme more queues than can be supported
because when XDP is enabled for retransmit XDP attempts to use a queue
per cpu. My standard queue count is 'queues=4'.
After loading the VM I run the relevant XDP test programs in,
./sammples/bpf
For this series I tested xdp1, xdp2, and xdp_tx_iptunnel. I usually test
with iperf (-d option to get bidirectional traffic), ping, and pktgen.
I also have a modified xdp1 that returns XDP_PASS on any packet to ensure
the normal traffic path to the stack continues to work with XDP loaded.
It would be great to automate this soon. At the moment I do it by hand
which is starting to get tedious.
v2: original series dropped trace points after merge.
Michael, I just want to apply this right now.
I don't think haggling over whether to allocate the adjust_head area
unconditionally or not is a blocker for this series going in. That
can be addressed trivially in a follow-on patch.
FYI it would just mean we revert most of this patchset except patches 2 and 3
though.
We want these new reset paths tested as much as possible and each day
we delay this series is detrimental towards that goal.
Thanks.
Well the point is to avoid resets completely, at the cost of extra 256 bytes
for packets > 128 bytes on ppc (64k pages) only.
Found a volunteer so I hope to have this idea tested on ppc Tuesday.
And really all we need to know is confirm whether this:
-#define MERGEABLE_BUFFER_MIN_ALIGN_SHIFT ((PAGE_SHIFT + 1) / 2)
+#define MERGEABLE_BUFFER_MIN_ALIGN_SHIFT (PAGE_SHIFT / 2 + 1)
affects performance in a measureable way.
Ok, but we still need to drop some packets with this way I believe, and
does it work if we allow to change the size of headroom in the future?
Thanks
So I would rather wait another day. But the patches themselves
look correct, from that POV.
Acked-by: Michael S. Tsirkin <m...@redhat.com>
but I would prefer that you waited another day for a Tested-by from me too.
