netdev - Re: [PATCH net-next 0/4] net: Convert some UDP tunnel drivers to NETDEV_PCPU_STAT

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Message-ID: <Z07t69eseT2+PzDj@debian>
Date: Tue, 3 Dec 2024 12:39:23 +0100
From: Guillaume Nault <gnault@...hat.com>
To: James Chapman <jchapman@...alix.com>
Cc: David Miller <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>, Eric Dumazet <edumazet@...gle.com>,
	netdev@...r.kernel.org, Simon Horman <horms@...nel.org>,
	David Ahern <dsahern@...nel.org>,
	Andrew Lunn <andrew+netdev@...n.ch>
Subject: Re: [PATCH net-next 0/4] net: Convert some UDP tunnel drivers to
 NETDEV_PCPU_STAT_DSTATS.

On Tue, Dec 03, 2024 at 08:12:29AM +0000, James Chapman wrote:
> Hi Guillaume,
> 
> I can work on similar changes to l2tp if you haven't already started work on
> it.

I haven't, so yes, please do. You can Cc me when submitting the patch,
so that I can ack it in time.

> James
> 
> On 02/12/2024 21:48, Guillaume Nault wrote:
> > VXLAN, Geneve and Bareudp use various device counters for managing
> > RX and TX statistics:
> > 
> >    * VXLAN uses the device core_stats for RX and TX drops, tstats for
> >      regular RX/TX counters and DEV_STATS_INC() for various types of
> >      RX/TX errors.
> > 
> >    * Geneve uses tstats for regular RX/TX counters and DEV_STATS_INC()
> >      for everything else, include RX/TX drops.
> > 
> >    * Bareudp, was recently converted to follow VXLAN behaviour, that is,
> >      device core_stats for RX and TX drops, tstats for regular RX/TX
> >      counters and DEV_STATS_INC() for other counter types.
> > 
> > Let's consolidate statistics management around the dstats counters
> > instead. This avoids using core_stats in VXLAN and Bareudp, as
> > core_stats is supposed to be used by core networking code only (and not
> > in drivers).  This also allows Geneve to avoid using atomic increments
> > when updating RX and TX drop counters, as dstats is per-cpu. Finally,
> > this also simplifies the code as all three modules now handle stats in
> > the same way and with only two different sets of counters (the per-cpu
> > dstats and the atomic DEV_STATS_INC()).
> > 
> > Patch 1 creates dstats helper functions that can be used outside of VRF
> > (before that, dstats was VRF-specific).
> > Patches 2 to 4 convert VXLAN, Geneve and Bareudp, one by one.
> > 
> > Guillaume Nault (4):
> >    vrf: Make pcpu_dstats update functions available to other modules.
> >    vxlan: Handle stats using NETDEV_PCPU_STAT_DSTATS.
> >    geneve: Handle stats using NETDEV_PCPU_STAT_DSTATS.
> >    bareudp: Handle stats using NETDEV_PCPU_STAT_DSTATS.
> > 
> >   drivers/net/bareudp.c          | 16 ++++++------
> >   drivers/net/geneve.c           | 12 ++++-----
> >   drivers/net/vrf.c              | 46 +++++++++-------------------------
> >   drivers/net/vxlan/vxlan_core.c | 28 ++++++++++-----------
> >   include/linux/netdevice.h      | 40 +++++++++++++++++++++++++++++
> >   5 files changed, 80 insertions(+), 62 deletions(-)
> > 
> 
> -- 
> James Chapman
> Katalix Systems Ltd
> https://katalix.com
> Catalysts for your Embedded Linux software development
>