Hi Ilya,
On 12/8/21 00:23, Ilya Maximets wrote:
On 11/24/21 22:23, Maxime Coquelin wrote:
This series introduces a new HXPS Tx mode alognside existing
XPS and static modes. The goal is to provide a mode where all
the transmit queues are used, whatever the number of PMD
threads. This may be used with Vhost-user ports, where the
guest application driving the Virtio device expects packets
to be distributed on all the queues.
As a preliminary step, in order to be able to validate the
feature at OVS level, the first patch introduces per-queue
basic statistics for Vhost-user ports. This patch is
complementary to David's patch [0] adding per-queue
statistics to DPDK ports using xstats.
The series also introduces two DPDK tests for Vhost-user
multiqueue, with and without HXPS enabled.
Maxime Coquelin (4):
netdev-dpdk: Introduce per rxq/txq Vhost-user statistics
dpif-netdev: Introduce Tx queue mode
dpif-netdev: Add HXPS Tx queue mode
system-dpdk: Add tests for HXPS
Documentation/automake.mk | 1 +
Documentation/topics/dpdk/hxps.rst | 51 ++++++++++
Documentation/topics/dpdk/index.rst | 1 +
lib/dpif-netdev.c | 95 ++++++++++++++----
lib/netdev-dpdk.c | 143 ++++++++++++++++++++++++++--
tests/system-dpdk.at | 135 ++++++++++++++++++++++++++
6 files changed, 399 insertions(+), 27 deletions(-)
create mode 100644 Documentation/topics/dpdk/hxps.rst
Hi, Maxime. Thanks for working on this.
I agree that this feature might be very useful for some deployments.
I didn't read the code any carefully, just glanced at it. But I have
a couple of high level comments:
1. I don't think that the test for the actual XPS mode implementation
should be part of a system-dpdk testsuite, as it's not actually
related to DPDK and doesn't require any system HW/ports/non-OVS
applications running in order to test it.
So, I think, that we should be able to do practically the same
testing, but with dummy interfaces, with a test placed in the
dpif-netdev.at or pmd.at (probably, latter).
To achieve that you'll need per-queue stats in netdev-dummy, but
implementation of these will be practically the same or even a
bit simpler as you did for vhost-user ports.
Per-queue stats for vhost-user ports might be good to have in
general, so that patch along with some simple test in system-dpdk.at
for them could be split from this patch set and sent separately.
Or dropped, if you think they are not valuable (?).
OK, I will work on adding per-queue stats to netdev-dummy. I agree it is
better to decouple the testing of this feature from DPDK, and it will
make the test being executed more often.
2. The test itself doesn't need a packet generator script, AFAICT.
You may just send some number of packets via dummy port changing
source or destination udp/tcp port affecting the packet hash this
way. For example, see the SEND_TCP_BOND_PKTS macro in the
tests/ofproto-dpif.at and how bonding rebalancing tests are using it.
Thanks for the pointer on SEND_TCP_BOND_PKTS, I agree this is better
this way. Also, using fuzzing as I did may have the drawback of seldomly
generate packets with hashes that would make them all ending into a
single queue.
3. Might be better instead of introduction of a specialized config
knob (other_config:hxps=true), to have a multi-choice knob like
other_config:xps-mode with 2 options 'default' and 'hash', where
'default' is a current way of tx queue distribution and it will
be a default value. 'hash' will be a new mode that uses packet
hash to choose the tx queue (what's implemented in this patch set).
Ok, makes sense.
What do you think?
Those are valid points, thanks for your suggestions.
Maxime
Best regards, Ilya Maximets.
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