utilities: Add revalidator measurement script and needed USDT probes.

This patch adds a Python script that can be used to analyze the
revalidator runs by providing statistics (including some real time
graphs).

The USDT events can also be captured to a file and used for
later offline analysis.

The following blog explains the Open vSwitch revalidator
implementation and how this tool can help you understand what is
happening in your system.

https://developers.redhat.com/articles/2022/10/19/open-vswitch-revalidator-process-explained

Signed-off-by: Eelco Chaudron <echaudro@redhat.com>
Acked-by: Adrian Moreno <amorenoz@redhat.com>
Acked-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>

1 files changed, 84 insertions, 0 deletions

diff --git a/Documentation/topics/usdt-probes.rst b/Documentation/topics/usdt-probes.rst
index 004817b1c..e527f43ba 100644
--- a/Documentation/topics/usdt-probes.rst
+++ b/Documentation/topics/usdt-probes.rst
@@ -214,6 +214,10 @@ Available probes in ``ovs_vswitchd``:
 - dpif_recv:recv_upcall
 - main:poll_block
 - main:run_start
+- revalidate_ukey\_\_:entry
+- revalidate_ukey\_\_:exit
+- udpif_revalidator:start_dump
+- udpif_revalidator:sweep_done
 
 
 dpif_netlink_operate\_\_:op_flow_del
@@ -328,6 +332,7 @@ probe main:run_start
 ~~~~~~~~~~~~~~~~~~~~
 
 **Description**:
+
 The ovs-vswitchd's main process contains a loop that runs every time some work
 needs to be done. This probe gets triggered every time the loop starts from the
 beginning. See also the ``main:poll_block`` probe below.
@@ -345,6 +350,7 @@ probe main:poll_block
 ~~~~~~~~~~~~~~~~~~~~~
 
 **Description**:
+
 The ovs-vswitchd's main process contains a loop that runs every time some work
 needs to be done. This probe gets triggered every time the loop is done, and
 it's about to wait for being re-started by a poll_block() call returning.
@@ -359,6 +365,84 @@ See also the ``main:run_start`` probe above.
 - ``utilities/usdt-scripts/bridge_loop.bt``
 
 
+revalidate_ukey\_\_:entry
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+**Description**:
+
+This probe gets triggered on entry of the revalidate_ukey__() function.
+
+**Arguments**:
+
+- *arg0*: ``(struct udpif *) udpif``
+- *arg1*: ``(struct udpif_key *) ukey``
+- *arg2*: ``(uint16_t) tcp_flags``
+- *arg3*: ``(struct ofpbuf *) odp_actions``
+- *arg4*: ``(struct recirc_refs *) recircs``
+- *arg5*: ``(struct xlate_cache *) xcache``
+
+**Script references**:
+
+- ``utilities/usdt-scripts/reval_monitor.py``
+
+
+revalidate_ukey\_\_:exit
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+**Description**:
+
+This probe gets triggered right before the revalidate_ukey__() function exits.
+
+**Arguments**:
+
+- *arg0*: ``(struct udpif *) udpif``
+- *arg1*: ``(struct udpif_key *) ukey``
+- *arg2*: ``(enum reval_result) result``
+
+**Script references**:
+
+*None*
+
+
+udpif_revalidator:start_dump
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+**Description**:
+
+The ovs-vswitchd's revalidator process contains a loop that runs every time
+revalidation work is needed. This probe gets triggered every time the
+dump phase has started.
+
+**Arguments**:
+
+- *arg0*: ``(struct udpif *) udpif``
+- *arg1*: ``(size_t) n_flows``
+
+**Script references**:
+
+- ``utilities/usdt-scripts/reval_monitor.py``
+
+
+udpif_revalidator:sweep_done
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+**Description**:
+
+The ovs-vswitchd's revalidator process contains a loop that runs every time
+revalidation work is needed. This probe gets triggered every time the
+sweep phase was completed.
+
+**Arguments**:
+
+- *arg0*: ``(struct udpif *) udpif``
+- *arg1*: ``(size_t) n_flows``
+- *arg2*: ``(unsigned) MIN(ofproto_max_idle, ofproto_max_revalidator)``
+
+**Script references**:
+
+- ``utilities/usdt-scripts/reval_monitor.py``
+
+
 Adding your own probes
 ----------------------