[ovs-dev] [PATCH] Use the correct logical datapath UUID as input for logical flow hash.

[Numan Siddique]

On Fri, Feb 23, 2018 at 3:24 AM, Jakub Sitnicki <jkbs at redhat.com> wrote:

> Use the logical switch/router UUID as hash input, instead of the UUID of
> the Datapath_Binding row, when calculating the hash value for lflows in
> the SBDB.
>
> Otherwise the hash value will never match the one computed from NBDB
> contents, which will force ovn-northd to constantly drop and attempt to
> re-insert all the lflows.
>
> This brings down the performance boost from caching the hash values
> computed for logical flows in SBDB down to the expected level:
>
>   Children      Self  Command     Shared Object        Symbol
> before:
>     76.19%     0.01%  ovn-northd  ovn-northd           [.] ovnnb_db_run
>     11.04%     0.43%  ovn-northd  ovn-northd           [.] ovn_lflow_find
> after:
>     75.16%     0.05%  ovn-northd  ovn-northd           [.] ovnnb_db_run
>      2.49%     0.17%  ovn-northd  ovn-northd           [.] ovn_lflow_find
>
> Fixes: 8bf332225d4a ("ovn-northd: Reduce amount of flow hashing.")
> Signed-off-by: Jakub Sitnicki <jkbs at redhat.com>
>

Acked-by: Numan Siddique <nusiddiq at redhat.com>
Tested-by: Numan Siddique <nusiddiq at redhat.com>


---
>  ovn/lib/ovn-util.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/ovn/lib/ovn-util.c b/ovn/lib/ovn-util.c
> index e9464e926..1761defd9 100644
> --- a/ovn/lib/ovn-util.c
> +++ b/ovn/lib/ovn-util.c
> @@ -339,7 +339,13 @@ sbrec_logical_flow_hash(const struct
> sbrec_logical_flow *lf)
>          return 0;
>      }
>
> -    return ovn_logical_flow_hash(&ld->header_.uuid,
> +    struct uuid ld_uuid;
> +    if (!smap_get_uuid(&ld->external_ids, "logical-switch", &ld_uuid) &&
> +        !smap_get_uuid(&ld->external_ids, "logical-router", &ld_uuid)) {
> +        return 0;
> +    }
> +
> +    return ovn_logical_flow_hash(&ld_uuid,
>                                   lf->table_id, lf->pipeline,
>                                   lf->priority, lf->match, lf->actions);
>  }
> --
> 2.14.3
>
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