Re: [ovs-dev] [PATCH net-next v4 03/10] net: openvswitch: shrink the mask array if necessary

[William Tu <u9012063@gmail.com>]

On Wed, Oct 16, 2019 at 5:53 AM <xiangxia.m.yue@gmail.com> wrote:
>
> From: Tonghao Zhang <xiangxia.m.yue@gmail.com>
>
> When creating and inserting flow-mask, if there is no available
> flow-mask, we realloc the mask array. When removing flow-mask,
> if necessary, we shrink mask array.
>
> Signed-off-by: Tonghao Zhang <xiangxia.m.yue@gmail.com>
> Tested-by: Greg Rose <gvrose8192@gmail.com>
> ---

LGTM
Acked-by: William Tu <u9012063@gmail.com>

On the other hand, maybe we should have an upper limit on the
mask cash size?

Regards,
William`
>  net/openvswitch/flow_table.c | 33 +++++++++++++++++++++++----------
>  1 file changed, 23 insertions(+), 10 deletions(-)
>
> diff --git a/net/openvswitch/flow_table.c b/net/openvswitch/flow_table.c
> index 0d1df53..237cf85 100644
> --- a/net/openvswitch/flow_table.c
> +++ b/net/openvswitch/flow_table.c
> @@ -693,6 +693,23 @@ static struct table_instance *table_instance_expand(struct table_instance *ti,
>         return table_instance_rehash(ti, ti->n_buckets * 2, ufid);
>  }
>
> +static void tbl_mask_array_delete_mask(struct mask_array *ma,
> +                                      struct sw_flow_mask *mask)
> +{
> +       int i;
> +
> +       /* Remove the deleted mask pointers from the array */
> +       for (i = 0; i < ma->max; i++) {
> +               if (mask == ovsl_dereference(ma->masks[i])) {
> +                       RCU_INIT_POINTER(ma->masks[i], NULL);
> +                       ma->count--;
> +                       kfree_rcu(mask, rcu);
> +                       return;
> +               }
> +       }
> +       BUG();
> +}
> +
>  /* Remove 'mask' from the mask list, if it is not needed any more. */
>  static void flow_mask_remove(struct flow_table *tbl, struct sw_flow_mask *mask)
>  {
> @@ -706,18 +723,14 @@ static void flow_mask_remove(struct flow_table *tbl, struct sw_flow_mask *mask)
>
>                 if (!mask->ref_count) {
>                         struct mask_array *ma;
> -                       int i;
>
>                         ma = ovsl_dereference(tbl->mask_array);
> -                       for (i = 0; i < ma->max; i++) {
> -                               if (mask == ovsl_dereference(ma->masks[i])) {
> -                                       RCU_INIT_POINTER(ma->masks[i], NULL);
> -                                       ma->count--;
> -                                       kfree_rcu(mask, rcu);
> -                                       return;
> -                               }
> -                       }
> -                       BUG();
> +                       tbl_mask_array_delete_mask(ma, mask);
> +
> +                       /* Shrink the mask array if necessary. */
> +                       if (ma->max >= (MASK_ARRAY_SIZE_MIN * 2) &&
> +                           ma->count <= (ma->max / 3))
> +                               tbl_mask_array_realloc(tbl, ma->max / 2);
>                 }
>         }
>  }
> --
> 1.8.3.1
>
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