On 7/2/2020 12:56 PM, Kevin Traynor wrote:
On 02/07/2020 12:18, Stokes, Ian wrote:
On 7/1/2020 3:08 PM, Kevin Traynor wrote:
On 01/07/2020 13:46, Ilya Maximets wrote:
On 7/1/20 1:46 PM, Kevin Traynor wrote:
On 01/07/2020 11:28, Stokes, Ian wrote:
Hi All,
While completing validation work for DPDK 18.11.9 and 19.11.3 it was
found that zero-copy for vhostuserclient devices is no longer possible.
Please see commit below from 18.11.9 (note this patch is also in DPDK
19.11.3)
Thanks catching this in your validation, it almost certainly wouldn't
have been caught otherwise.
Definitely a good catch. Thanks.
commit 81e025d7ed6a802845909df6fb90505508dc0fbf
Author: Xuan Ding <xuan.d...@intel.com>
Date: Wed Apr 29 02:59:46 2020 +0000
vhost: prevent zero-copy with incompatible client mode
[ upstream commit 715070ea10e6da1169deef2a3ea77ae934b4c333 ]
In server mode, virtio-user inits under the assumption that vhost-user
supports a list of features. However, this could be problematic when
in_order feature is negotiated but not supported by vhost-user when
enables dequeue_zero_copy later.
Add handling when vhost-user enables dequeue_zero_copy as client.
IIUC, this patch basically drops the feature for perfectly fine cases
with VMs. While it was intended to forbid running zero-copy with virtio-user
it breaks a different usecase blocking the feature entirely.
Isn't it an API breakage? IMHO, it should not have been backported in the
first place, since dropping the feature is not what usually expected in
stable releases. And this must be in release notes anyway.
I think, the right solution here should be to make a patch to handle specific
virtio-user case and stop blocking valid cases and release new DPDK stable
versions for already released ones.
If it's too hard to make a patch or no-one wants to work on this, just revert
these changes from stable branches and release a new stable DPDK version
for both 18.11 and 19.11. But anyway, regression should be addressed in DPDK
before 20.11 or it will block OVS upgrade to that version.
It is not in a released 18.11. It was caught by Ian's team as part of
18.11.9-rc testing.
OK so it seems like we can use 18.11.9 for the 2.11 and 2.13 branches as
it will have this patch reverted.
Is there an 18.11.9 RC3 planned? We can test it if it's of use.
I've just pushed it to the 18:11 branch, can you test with that?
I wasn't planning on an rc3 at this stage for just this patch, but if
you need a tarball for testing automation or something, let me know and
I can create it.
Thanks Kevin,
the team tested on our side and see the expected behavior now. Looks
good to go.
Regards
Ian
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