[ovs-dev] [PATCH v3 0/5] Fast OVSDB resync after restart or fail-over.

[Han Zhou]

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On Mon, Feb 25, 2019 at 9:25 AM Han Zhou <zhouhan at gmail.com> wrote:
>
> In scalability test with ovn-scale-test, ovsdb-server SB load is not a
> problem at least with 1k HVs. However, if we restart the ovsdb-server,
> depending on the number of HVs and scale of logical objects, e.g. the
> number of logical ports, ovsdb-server of SB become an obvious bottleneck.
>
> In our test with 1k HVs and 20k logical ports (200 lport * 100 lswitches
> connected by one single logical router). Restarting ovsdb-server of SB
> resulted in 100% CPU of ovsdb-server for more than 1 hour. All HVs (and
> northd) are reconnecting and resyncing the big amount of data at the same
> time.
>
> Similar problem would happen in failover scenario. With active-active
> cluster, the problem can be aleviated slightly, because only 1/3 (assuming
> it is 3-node cluster) of the HVs will need to resync data from new servers,
> but it is still a serious problem.
>
> For detailed discussions for the problem and solutions, see:
> https://mail.openvswitch.org/pipermail/ovs-discuss/2018-October/047591.html
>
> The patches implements the proposal in that discussion. It introduces
> a new method monitor_cond_since to enable client to request changes that
> happened after a specific point so that the data has been cached already
> in client are not re-transfered. Scalability test shows dramatic improvement.
> All HVs finishes sync as soon as they reconnect since there is no new data
> to be transfered.
>
> The current patches supports all 3 modes of ovsdb-server, but only clustered
> mode can benefit from it, since it is the only one that supports transaction
> id out of the box.
>
> ---
> v1 -> v2: fix the unused variable in patch 6/7 reported by 0-day.
> v2 -> v3: first 2 in the 7 were merged. Revised 1/5 addressing Ben's
> comment on the json cache hmap.
>
> Han Zhou (5):
>   ovsdb-monitor: Refactor ovsdb monitor implementation.
>   ovsdb-server: Transaction history tracking.
>   ovsdb-monitor: Support monitor_cond_since.
>   ovsdb-idl.c: Support monitor_cond_since method in C IDL.
>   ovsdb-idl.c: Fast resync from server when connection reset.
>
>  Documentation/ref/ovsdb-server.7.rst |  78 +++++-
>  lib/ovsdb-idl.c                      | 229 ++++++++++++----
>  ovsdb/jsonrpc-server.c               | 101 +++++--
>  ovsdb/monitor.c                      | 516 ++++++++++++++++++++++-------------
>  ovsdb/monitor.h                      |  16 +-
>  ovsdb/ovsdb-client.1.in              |  28 +-
>  ovsdb/ovsdb-client.c                 | 104 ++++++-
>  ovsdb/ovsdb-server.c                 |  11 +
>  ovsdb/ovsdb.c                        |   3 +
>  ovsdb/ovsdb.h                        |  10 +
>  ovsdb/transaction.c                  | 117 +++++++-
>  ovsdb/transaction.h                  |   4 +
>  tests/ovsdb-monitor.at               | 301 +++++++++++++++++++-
>  13 files changed, 1232 insertions(+), 286 deletions(-)
>
> --
> 2.1.0
>