netdev - Re: [RFC 00/14] netlink/hierarchical stats

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Message-ID: <CAJieiUgF4tHtqbzwC4g4HDOtss=Q14auyG=7WZXnQHaj6DXSmQ@mail.gmail.com>
Date:   Wed, 30 Jan 2019 14:14:34 -0800
From:   Roopa Prabhu <roopa@...ulusnetworks.com>
To:     Jakub Kicinski <jakub.kicinski@...ronome.com>
Cc:     David Miller <davem@...emloft.net>, oss-drivers@...ronome.com,
        netdev <netdev@...r.kernel.org>,
        Jiří Pírko <jiri@...nulli.us>,
        Florian Fainelli <f.fainelli@...il.com>,
        Andrew Lunn <andrew@...n.ch>,
        Michal Kubecek <mkubecek@...e.cz>,
        David Ahern <dsahern@...il.com>,
        Simon Horman <simon.horman@...ronome.com>,
        "Brandeburg, Jesse" <jesse.brandeburg@...el.com>,
        maciejromanfijalkowski@...il.com, vasundhara-v.volam@...adcom.com,
        Michael Chan <michael.chan@...adcom.com>, shalomt@...lanox.com,
        Ido Schimmel <idosch@...lanox.com>
Subject: Re: [RFC 00/14] netlink/hierarchical stats

On Mon, Jan 28, 2019 at 3:45 PM Jakub Kicinski
<jakub.kicinski@...ronome.com> wrote:
>
> Hi!
>
> As I tried to explain in my slides at netconf 2018 we are lacking
> an expressive, standard API to report device statistics.
>
> Networking silicon generally maintains some IEEE 802.3 and/or RMON
> statistics.  Today those all end up in ethtool -S.  Here is a simple
> attempt (admittedly very imprecise) of counting how many names driver
> authors invented for IETF RFC2819 etherStatsPkts512to1023Octets
> statistics (RX and TX):
>
> $ git grep '".*512.*1023.*"' -- drivers/net/ | \
>     sed -e 's/.*"\(.*\)".*/\1/' | sort | uniq | wc -l
> 63
>
> Interestingly only two drivers in the tree use the name the standard
> gave us (etherStatsPkts512to1023, modulo case).
>
> I set out to working on this set in an attempt to give drivers a way
> to express clearly to user space standard-compliant counters.
>
> Second most common use for custom statistics is per-queue counters.
> This is where the "hierarchical" part of this set comes in, as
> groups can be nested, and user space tools can handle the aggregation
> inside the groups if needed.
>
> This set also tries to address the problem of users not knowing if
> a statistic is reported by hardware or the driver.  Many modern drivers
> use some prefix in ethtool -S to indicate MAC/PHY stats.  At a quick
> glance: Netronome uses "mac.", Intel "port." and Mellanox "_phy".
> In this set, netlink attributes describe whether a group of statistics
> is RX or TX, maintained by device or driver.
>
> The purpose of this patch set is _not_ to replace ethtool -S.  It is
> an incredibly useful tool, and we will certainly continue using it.
> However, for standard-based and commonly maintained statistics a more
> structured API seems warranted.
>
> There are two things missing from these patches, which I initially
> planned to address as well: filtering, and refresh rate control.
>
> Filtering doesn't need much explanation, users should be able to request
> only a subset of statistics (like only SW stats or only given ID).  The
> bitmap of statistics in each group is there for filtering later on.
>
> By refresh control I mean the ability for user space to indicate how
> "fresh" values it expects.  Sometimes reading the HW counters requires
> slow register reads or FW communication, in such cases drivers may cache
> the result.  (Privileged) user space should be able to add a "not older
> than" timestamp to indicate how fresh statistics it expects.  And vice
> versa, drivers can then also put the timestamp of when the statistics
> were last refreshed in the dump for more precise bandwidth estimation.


Jakub, Glad to see hw stats in the RTM_*STATS api. I do see you
mention 'partial' support for ethtool stats. I understand the reason
you say its partial.
But while at it, why not also include the ability to have driver
extensible stats here ? ie make it complete. We have talked about
making all hw stats available
via the RTM_*STATS api in the past..., so just want to make sure the
new HSTATS infra you are adding to the RTM_*STATS api
covers or at-least makes it possible to include driver extensible
stats in the future where the driver gets to define the stats id +
value (This is very useful).
 It would be nice if you can account for that in this new HSTATS API.





>
> Jakub Kicinski (14):
>   nfp: remove unused structure
>   nfp: constify parameter to nfp_port_from_netdev()
>   net: hstats: add basic/core functionality
>   net: hstats: allow hierarchies to be built
>   nfp: very basic hstat support
>   net: hstats: allow iterators
>   net: hstats: help in iteration over directions
>   nfp: hstats: make use of iteration for direction
>   nfp: hstats: add driver and device per queue statistics
>   net: hstats: add IEEE 802.3 and common IETF MIB/RMON stats
>   nfp: hstats: add IEEE/RMON ethernet port/MAC stats
>   net: hstats: add markers for partial groups
>   nfp: hstats: add a partial group of per-8021Q prio stats
>   Documentation: networking: describe new hstat API
>
>  Documentation/networking/hstats.rst           | 590 +++++++++++++++
>  .../networking/hstats_flow_example.dot        |  11 +
>  Documentation/networking/index.rst            |   1 +
>  drivers/net/ethernet/netronome/nfp/Makefile   |   1 +
>  .../net/ethernet/netronome/nfp/nfp_hstat.c    | 474 ++++++++++++
>  drivers/net/ethernet/netronome/nfp/nfp_main.c |   1 +
>  drivers/net/ethernet/netronome/nfp/nfp_main.h |   2 +
>  drivers/net/ethernet/netronome/nfp/nfp_net.h  |  10 +-
>  .../ethernet/netronome/nfp/nfp_net_common.c   |   1 +
>  .../net/ethernet/netronome/nfp/nfp_net_repr.h |   2 +-
>  drivers/net/ethernet/netronome/nfp/nfp_port.c |   2 +-
>  drivers/net/ethernet/netronome/nfp/nfp_port.h |   2 +-
>  include/linux/netdevice.h                     |   9 +
>  include/net/hstats.h                          | 176 +++++
>  include/uapi/linux/if_link.h                  | 107 +++
>  net/core/Makefile                             |   2 +-
>  net/core/hstats.c                             | 682 ++++++++++++++++++
>  net/core/rtnetlink.c                          |  21 +
>  18 files changed, 2084 insertions(+), 10 deletions(-)
>  create mode 100644 Documentation/networking/hstats.rst
>  create mode 100644 Documentation/networking/hstats_flow_example.dot
>  create mode 100644 drivers/net/ethernet/netronome/nfp/nfp_hstat.c
>  create mode 100644 include/net/hstats.h
>  create mode 100644 net/core/hstats.c
>
> --
> 2.19.2
>