netdev - Re: [PATCH net-next v3 0/6] net: mpls: Allow users to configure more labels per route

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Date:   Mon, 3 Apr 2017 09:14:58 +0100
From:   Robert Shearman <rshearma@...cade.com>
To:     David Ahern <dsa@...ulusnetworks.com>, <netdev@...r.kernel.org>
CC:     <roopa@...ulusnetworks.com>, <ebiederm@...ssion.com>
Subject: Re: [PATCH net-next v3 0/6] net: mpls: Allow users to configure more
 labels per route

On 31/03/17 15:13, David Ahern wrote:
> Increase the maximum number of new labels for MPLS routes from 2 to 30.
>
> To keep memory consumption in check, the labels array is moved to the end
> of mpls_nh and mpls_iptunnel_encap structs as a 0-sized array. Allocations
> use the maximum number of labels across all nexthops in a route for LSR
> and the number of labels configured for LWT.
>
> The mpls_route layout is changed to:
...
>
> Meaning the via follows its mpls_nh providing better locality as the
> number of labels increases. UDP_RR tests with namespaces shows no impact
> to a modest performance increase with this layout for 1 or 2 labels and
> 1 or 2 nexthops.
>
> mpls_route allocation size is limited to 4096 bytes allowing on the
> order of 30 nexthops with 30 labels (or more nexthops with fewer
> labels). LWT encap shares same maximum number of labels as mpls routing.
>
> v3
> - initialize n_labels to 0 in case RTA_NEWDST is not defined; detected
>   by the kbuild test robot
>
> v2
> - updates per Eric's comments
>   + added patch to ensure all reads of rt_nhn_alive and nh_flags in
>     the packet path use READ_ONCE and all writes via event handlers
>     use WRITE_ONCE
>
>   + limit mpls_route size to 4096 (PAGE_SIZE for most arch)
>
>   + mostly killed use of MAX_NEW_LABELS; it exists only for common
>     limit between lwt and routing paths
>
> David Ahern (6):
>   net: mpls: rt_nhn_alive and nh_flags should be accessed using
>     READ_ONCE
>   net: mpls: Convert number of nexthops to u8
>   net: mpls: change mpls_route layout
>   net:mpls: Limit memory allocation for mpls_route
>   net: mpls: bump maximum number of labels
>   net: mpls: Increase max number of labels for lwt encap
>
>  include/net/mpls_iptunnel.h |   5 +-
>  net/mpls/af_mpls.c          | 210 +++++++++++++++++++++++++++++---------------
>  net/mpls/internal.h         |  61 +++++++++----
>  net/mpls/mpls_iptunnel.c    |  13 ++-
>  4 files changed, 196 insertions(+), 93 deletions(-)
>

Acked-by: Robert Shearman <rshearma@...cade.com>