Re: [PATCH net-next 03/21] ethtool, stats: introduce standard XDP statistics - Toke Høiland-Jørgensen

From: "Toke Høiland-Jørgensen" <toke@redhat.com>
To: Alexander Lobakin <alexandr.lobakin@intel.com>,
	Saeed Mahameed <saeed@kernel.org>
Cc: Michal Kubecek <mkubecek@suse.cz>, Andrew Lunn <andrew@lunn.ch>,
	Song Liu <songliubraving@fb.com>,
	Vladyslav Tarasiuk <vladyslavt@nvidia.com>,
	Sameeh Jubran <sameehj@amazon.com>,
	"Michael S. Tsirkin" <mst@redhat.com>, Yonghong Song <yhs@fb.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Zheng Yongjun <zhengyongjun3@huawei.com>,
	Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
	Ioana Ciornei <ioana.ciornei@nxp.com>,
	Petr Vorel <petr.vorel@gmail.com>,
	Alexander Duyck <alexanderduyck@fb.com>,
	Jian Shen <shenjian15@huawei.com>,
	Arthur Kiyanovski <akiyano@amazon.com>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Jonathan Corbet <corbet@lwn.net>,
	linux-doc@vger.kernel.org,
	John Fastabend <john.fastabend@gmail.com>,
	Russell King <linux@armlinux.org.uk>,
	Michal Kubiak <michal.kubiak@intel.com>,
	Martin Habets <habetsm.xilinx@gmail.com>,
	virtualization@lists.linux-foundation.org,
	Guy Tzalik <gtzalik@amazon.com>,
	YueHaibing <yuehaibing@huawei.com>,
	Maciej Fijalkowski <maciej.fijalkowski@intel.com>,
	Jesper Dangaard Brouer <hawk@kernel.org>,
	Arnd Bergmann <arnd@arndb.de>, Ido Schimmel <idosch@nvidia.com>,
	Lukasz Czapnik <lukasz.czapnik@intel.com>,
	KP Singh <kpsingh@kernel.org>,
	Andrii Nakryiko <andrii@kernel.org>,
	Claudiu Manoil <claudiu.manoil@nxp.com>,
	Alexander Lobakin <alexandr.lobakin@intel.com>,
	Dan Murphy <dmurphy@ti.com>, Jakub Kicinski <kuba@kernel.org>,
	Shay Agroskin <shayagr@amazon.com>,
	Marcin Wojtas <mw@semihalf.com>,
	Johannes Berg <johannes@sipsolutions.net>,
	Danielle Ratson <danieller@nvidia.com>,
	Michal Swiatkowski <michal.swiatkowski@intel.com>,
	netdev@vger.kernel.org, bpf@vger.kernel.org,
	linux-kernel@vger.kernel.org, Martin KaFai Lau <kafai@fb.com>,
	Edward Cree <ecree.xilinx@gmail.com>,
	Netanel Belgazal <netanel@amazon.com>,
	Marcin Kubiak <marcin.kubiak@intel.com>,
	Yangbo Lu <yangbo.lu@nxp.com>, Saeed Bishara <saeedb@amazon.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	"David S. Miller" <davem@davemloft.net>,
	Heiner Kallweit <hkallweit1@gmail.com>
Subject: Re: [PATCH net-next 03/21] ethtool, stats: introduce standard XDP statistics
Date: Mon, 08 Nov 2021 12:37:54 +0100	[thread overview]
Message-ID: <87v912ri7h.fsf@toke.dk> (raw)
In-Reply-To: <20211105164453.29102-1-alexandr.lobakin@intel.com>

Alexander Lobakin <alexandr.lobakin@intel.com> writes:

> From: Alexander Lobakin <alexandr.lobakin@intel.com>
> Date: Tue, 26 Oct 2021 11:23:23 +0200
>
>> From: Saeed Mahameed <saeed@kernel.org>
>> Date: Tue, 03 Aug 2021 16:57:22 -0700
>> 
>> [ snip ]
>> 
>> > XDP is going to always be eBPF based ! why not just report such stats
>> > to a special BPF_MAP ? BPF stack can collect the stats from the driver
>> > and report them to this special MAP upon user request.
>> 
>> I really dig this idea now. How do you see it?
>> <ifindex:channel:stat_id> as a key and its value as a value or ...?
>
> Ideas, suggestions, anyone?

I don't like the idea of putting statistics in a map instead of the
regular statistics counters. Sure, for bespoke things people want to put
into their XDP programs, use a map, but for regular packet/byte
counters, update the regular counters so XDP isn't "invisible".

As Jesper pointed out, batching the updates so the global counters are
only updated once per NAPI cycle is the way to avoid a huge performance
overhead of this...

-Toke

_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization