[ovs-dev] [PATCH v3 1/2] dpctl: dpif: add kernel datapath cache hit output

Flavio Leitner fbl at sysclose.org
Wed Mar 3 20:44:26 UTC 2021


On Wed, Mar 03, 2021 at 02:52:33PM +0100, Eelco Chaudron wrote:
> This patch adds cache usage statistics to the output:
> 
> $ ovs-dpctl show
> system at ovs-system:
>   lookups: hit:24 missed:71 lost:0
>   flows: 0
>   masks: hit:334 total:0 hit/pkt:3.52
>   cache: hit:4 hit rate:4.2105%

nit: maybe the maintainer can fix that to be 2 digits as the code below.

>   port 0: ovs-system (internal)
>   port 1: genev_sys_6081 (geneve: packet_type=ptap)
>   port 2: br-int (internal)
>   port 3: br-ex (internal)
>   port 4: eth2
>   port 5: sw1p1 (internal)
>   port 6: sw0p4 (internal)
> 
> Signed-off-by: Eelco Chaudron <echaudro at redhat.com>
> ---
> v2: - Changed precision to 2 digits
>     - Handle missing kernel feature at netlink level
> v3: - Rebase on the latest master branch
> 
>  datapath/linux/compat/include/linux/openvswitch.h |    2 +-
>  lib/dpctl.c                                       |    9 +++++++++
>  lib/dpif-netdev.c                                 |    1 +
>  lib/dpif-netlink.c                                |    9 +++++++++
>  lib/dpif.h                                        |    2 ++
>  5 files changed, 22 insertions(+), 1 deletion(-)
> 
> diff --git a/datapath/linux/compat/include/linux/openvswitch.h b/datapath/linux/compat/include/linux/openvswitch.h
> index 875de2025..690d78871 100644
> --- a/datapath/linux/compat/include/linux/openvswitch.h
> +++ b/datapath/linux/compat/include/linux/openvswitch.h
> @@ -122,8 +122,8 @@ struct ovs_dp_megaflow_stats {
>  	__u64 n_mask_hit;	 /* Number of masks used for flow lookups. */
>  	__u32 n_masks;		 /* Number of masks for the datapath. */
>  	__u32 pad0;		 /* Pad for future expension. */
> +	__u64 n_cache_hit;       /* Number of cache matches for flow lookups. */

another nit: the datapath uses tab + spaces.

Otherwise:
Acked-by: Flavio Leitner <fbl at sysclose.org>

Thanks
fbl


>  	__u64 pad1;		 /* Pad for future expension. */
> -	__u64 pad2;		 /* Pad for future expension. */
>  };
>  
>  struct ovs_vport_stats {
> diff --git a/lib/dpctl.c b/lib/dpctl.c
> index ef8ae7402..acc677974 100644
> --- a/lib/dpctl.c
> +++ b/lib/dpctl.c
> @@ -611,6 +611,15 @@ show_dpif(struct dpif *dpif, struct dpctl_params *dpctl_p)
>              dpctl_print(dpctl_p, "  masks: hit:%"PRIu64" total:%"PRIu32
>                                   " hit/pkt:%.2f\n",
>                          stats.n_mask_hit, stats.n_masks, avg);
> +
> +            if (stats.n_cache_hit != UINT64_MAX) {
> +                double avg_hits = n_pkts ?
> +                    (double) stats.n_cache_hit / n_pkts * 100 : 0.0;
> +
> +                dpctl_print(dpctl_p,
> +                            "  cache: hit:%"PRIu64" hit rate:%.2f%%\n",
> +                            stats.n_cache_hit, avg_hits);
> +            }
>          }
>      }
>  
> diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
> index 816945375..c3d3aac36 100644
> --- a/lib/dpif-netdev.c
> +++ b/lib/dpif-netdev.c
> @@ -2025,6 +2025,7 @@ dpif_netdev_get_stats(const struct dpif *dpif, struct dpif_dp_stats *stats)
>      }
>      stats->n_masks = UINT32_MAX;
>      stats->n_mask_hit = UINT64_MAX;
> +    stats->n_cache_hit = UINT64_MAX;
>  
>      return 0;
>  }
> diff --git a/lib/dpif-netlink.c b/lib/dpif-netlink.c
> index ceb56c685..392b894c5 100644
> --- a/lib/dpif-netlink.c
> +++ b/lib/dpif-netlink.c
> @@ -672,9 +672,18 @@ dpif_netlink_get_stats(const struct dpif *dpif_, struct dpif_dp_stats *stats)
>              stats->n_masks = dp.megaflow_stats->n_masks;
>              stats->n_mask_hit = get_32aligned_u64(
>                  &dp.megaflow_stats->n_mask_hit);
> +            stats->n_cache_hit = get_32aligned_u64(
> +                &dp.megaflow_stats->n_cache_hit);
> +
> +            if (!stats->n_cache_hit) {
> +                /* Old kernels don't use this field and always
> +                 * report zero instead. Disable this stat. */
> +                stats->n_cache_hit = UINT64_MAX;
> +            }
>          } else {
>              stats->n_masks = UINT32_MAX;
>              stats->n_mask_hit = UINT64_MAX;
> +            stats->n_cache_hit = UINT64_MAX;
>          }
>          ofpbuf_delete(buf);
>      }
> diff --git a/lib/dpif.h b/lib/dpif.h
> index ecda896c7..600e4522c 100644
> --- a/lib/dpif.h
> +++ b/lib/dpif.h
> @@ -429,6 +429,8 @@ struct dpif_dp_stats {
>      uint64_t n_missed;          /* Number of flow table misses. */
>      uint64_t n_lost;            /* Number of misses not sent to userspace. */
>      uint64_t n_flows;           /* Number of flows present. */
> +    uint64_t n_cache_hit;       /* Number of mega flow mask cache hits for
> +                                   flow table matches. */
>      uint64_t n_mask_hit;        /* Number of mega flow masks visited for
>                                     flow table matches. */
>      uint32_t n_masks;           /* Number of mega flow masks. */
> 

-- 
fbl


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