[ovs-dev] [PATCH 0/3]: dpif-netdev: Detailed PMD performance metrics and supervision

[Jan Scheurich]

The run-time performance of PMDs is often difficult to understand and trouble-shoot. The existing PMD statistics counters only provide a coarse grained average picture. At packet rates of several Mpps sporadic drops of packet bursts happen at sub-millisecond time scales and are impossible to capture and analyze with existing tools.

This patch set refactors the existing PMD statistics into a dedicated submodule and collects a large number of important PMD performance metrics per PMD iteration, maintaining histograms and circular histories for iteration metrics and millisecond averages. To capture sporadic drop events, the patch set can be configured to monitor iterations for suspicious metrics and to log the neighborhood of such iterations for off-line analysis.

The extra cost for the performance metric collection and the supervision has been measured to be in the order of 1% compared to the base commit in a phy-to-phy setup with VXLAN tunnels (two datapath passes per packet). We believe this is fast enough to not warrant a build- or run-time configuration option to disable this.

The patch set is based on commit 3e90f7d7 (Sep 6) on branch dpdk_merge in Darrel's OVS repo. The first patch in the series fully includes the changes proposed in Darrel's earlier "[patch_v5 0/3] dpif-netdev: Fix and refactor pmd stats" https://mail.openvswitch.org/pipermail/ovs-dev/2017-August/337686.html.


Jan Scheurich (3)
	Refactor PMD performance into dpif-netdev-perf
	Detailed performance stats for PMDs
	Detection and logging of suspicious PMD iterations


lib/automake.mk        |   2 +
 lib/dp-packet.h        |   2 +
 lib/dpif-netdev-perf.c | 512 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 lib/dpif-netdev-perf.h | 317 ++++++++++++++++++++++++++++++++++++++
 lib/dpif-netdev.c      | 438 +++++++++++++++++++++++++++++-----------------------
 lib/netdev-dpdk.c      |  28 +++-
 lib/netdev-dpdk.h      |  14 ++
 lib/ovs-atomic.h       |   1 +
 ofproto/ofproto-dpif.c |   3 +-
 tests/pmd.at           |  22 ++-
 10 files changed, 1133 insertions(+), 206 deletions(-)