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

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Date:   Mon, 28 Jan 2019 15:44:53 -0800
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     davem@...emloft.net
Cc:     oss-drivers@...ronome.com, netdev@...r.kernel.org,
        jiri@...nulli.us, f.fainelli@...il.com, andrew@...n.ch,
        mkubecek@...e.cz, dsahern@...il.com, simon.horman@...ronome.com,
        jesse.brandeburg@...el.com, maciejromanfijalkowski@...il.com,
        vasundhara-v.volam@...adcom.com, michael.chan@...adcom.com,
        shalomt@...lanox.com, idosch@...lanox.com,
        Jakub Kicinski <jakub.kicinski@...ronome.com>
Subject: [RFC 00/14] netlink/hierarchical stats

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 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