[ovs-dev] [PATCH v10 3/5] dpif-netdev: split out generic lookup function

Ian Stokes ian.stokes at intel.com
Wed Jul 10 17:48:35 UTC 2019


On 7/9/2019 1:34 PM, Harry van Haaren wrote:
> This commit splits the generic hash-lookup-verify
> function to its own file. In doing so, we must move
> some MACRO definitions to dpif-netdev.h
> 
> Signed-off-by: Harry van Haaren <harry.van.haaren at intel.com>
> Tested-by: Malvika Gupta <malvika.gupta at arm.com>
> 

Thanks Harry, some feedback below.

> ---
> 
> v10:
> - Rebase fixups from previous patch changes
> - Add copyright as suggested in review (Ian)
> 
> v6:
> - Fixup some checkpatch warnings on whitespace with MACROs (Ilya)
> - Other MACROs function incorrectly when checkpatch is happy,
>    so using the functional version without space after the ( character.
>    This prints a checkpatch warning, but I see no way to fix it.
> ---
>   lib/automake.mk                  |  1 +
>   lib/dpif-netdev-lookup-generic.c | 95 ++++++++++++++++++++++++++++++++
>   lib/dpif-netdev.c                | 82 +--------------------------
>   lib/dpif-netdev.h                | 16 ++++++
>   4 files changed, 113 insertions(+), 81 deletions(-)
>   create mode 100644 lib/dpif-netdev-lookup-generic.c
> 

<snip>

> +
> +uint32_t
> +dpcls_subtable_lookup_generic(struct dpcls_subtable *subtable,
> +                              uint32_t keys_map,
> +                              const struct netdev_flow_key *keys[],
> +                              struct dpcls_rule **rules)
> +{
> +        int i;
> +        /* Compute hashes for the remaining keys.  Each search-key is
> +         * masked with the subtable's mask to avoid hashing the wildcarded
> +         * bits. */
> +        uint32_t hashes[NETDEV_MAX_BURST];
> +        ULLONG_FOR_EACH_1(i, keys_map) {
> +            hashes[i] = netdev_flow_key_hash_in_mask(keys[i],
> +                                                     &subtable->mask);
> +        }
> +
> +        /* Lookup. */
> +        const struct cmap_node *nodes[NETDEV_MAX_BURST];
> +        uint32_t found_map =
> +                cmap_find_batch(&subtable->rules, keys_map, hashes, nodes);

I would prefer to see

uint32_t found_map = cmap_find_batch(&subtable->rules,
                                      keys_map, hashes, nodes);

or alternatively you could declare uint32_t found_map at the beginning 
of the function so that way cmap_find_batch and arguments should be able 
to stay on the same line.

> +        /* Check results.  When the i-th bit of found_map is set, it means
> +         * that a set of nodes with a matching hash value was found for the
> +         * i-th search-key.  Due to possible hash collisions we need to check
> +         * which of the found rules, if any, really matches our masked
> +         * search-key. */
> +        ULLONG_FOR_EACH_1(i, found_map) {
> +            struct dpcls_rule *rule;
> +
> +            CMAP_NODE_FOR_EACH (rule, cmap_node, nodes[i]) {
> +                if (OVS_LIKELY(dpcls_rule_matches_key(rule, keys[i]))) {
> +                    rules[i] = rule;
> +                    /* Even at 20 Mpps the 32-bit hit_cnt cannot wrap
> +                     * within one second optimization interval. */
> +                    subtable->hit_cnt++;
> +                    goto next;
> +                }
> +            }
> +            /* None of the found rules was a match.  Reset the i-th bit to
> +             * keep searching this key in the next subtable. */
> +            ULLONG_SET0(found_map, i);  /* Did not match. */
> +        next:
> +            ;                     /* Keep Sparse happy. */
> +        }
> +
> +        return found_map;
> +}
> diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
> index 2414103d8..190cc8918 100644
> --- a/lib/dpif-netdev.c
> +++ b/lib/dpif-netdev.c
> @@ -235,14 +235,6 @@ struct dpcls {
>       struct pvector subtables;
>   };
>   

<snip>

>   /* Data structure to keep packet order till fastpath processing. */
>   struct dp_packet_flow_map {
>       struct dp_packet *packet;
> @@ -260,8 +252,6 @@ static bool dpcls_lookup(struct dpcls *cls,
>                            const struct netdev_flow_key *keys[],
>                            struct dpcls_rule **rules, size_t cnt,
>                            int *num_lookups_p);
> -static bool dpcls_rule_matches_key(const struct dpcls_rule *rule,
> -                            const struct netdev_flow_key *target);

I know you are only removing the function prototype above, but a new 
line here added would look better as well just to split the prototypes 
from the comments for the define section below for the meter flags.

>   /* Set of supported meter flags */
>   #define DP_SUPPORTED_METER_FLAGS_MASK \
>       (OFPMF13_STATS | OFPMF13_PKTPS | OFPMF13_KBPS | OFPMF13_BURST)
> @@ -2741,27 +2731,6 @@ netdev_flow_key_init_masked(struct netdev_flow_key *dst,
>                               (dst_u64 - miniflow_get_values(&dst->mf)) * 8);
>   }
>   

<snip>

>   /* For each miniflow in 'keys' performs a classifier lookup writing the result
>    * into the corresponding slot in 'rules'.  If a particular entry in 'keys' is
>    * NULL it is skipped.
> diff --git a/lib/dpif-netdev.h b/lib/dpif-netdev.h
> index 3d23743bd..3c3cc65ef 100644
> --- a/lib/dpif-netdev.h
> +++ b/lib/dpif-netdev.h
> @@ -52,6 +52,14 @@ struct netdev_flow_key {
>       uint64_t buf[FLOW_MAX_PACKET_U64S];
>   };
>   
> +/* A rule to be inserted to the classifier. */
> +struct dpcls_rule {
> +    struct cmap_node cmap_node;   /* Within struct dpcls_subtable 'rules'. */
> +    struct netdev_flow_key *mask; /* Subtable's mask. */
> +    struct netdev_flow_key flow;  /* Matching key. */
> +    /* 'flow' must be the last field, additional space is allocated here. */
> +};
> +
>   /* Lookup function for a subtable in the dpcls. This function is called
>    * by each subtable with an array of packets, and a bitmask of packets to
>    * perform the lookup on. Using a function pointer gives flexibility to
> @@ -93,6 +101,14 @@ struct dpcls_subtable {
>       /* 'mask' must be the last field, additional space is allocated here. */
>   };
>   
> +/* Iterate through netdev_flow_key TNL u64 values specified by 'FLOWMAP'. */
> +#define NETDEV_FLOW_KEY_FOR_EACH_IN_FLOWMAP(VALUE, KEY, FLOWMAP)   \
> +    MINIFLOW_FOR_EACH_IN_FLOWMAP (VALUE, &(KEY)->mf, FLOWMAP)

Might be better to move the define to the head of the file along with 
the existing defines.

> +
Minor: A one line comment for this prototype.

> +bool dpcls_rule_matches_key(const struct dpcls_rule *rule,
> +                            const struct netdev_flow_key *target);
> +
> +
>   #ifdef  __cplusplus
>   }
>   #endif
>

Regards
Ian






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