From: Jakub Kicinski <kuba@kernel•org>
To: Jesper Dangaard Brouer <hawk@kernel•org>
Cc: Simon Schippers <simon@schippers-hamm•de>,
Paolo Abeni <pabeni@redhat•com>,
netdev@vger•kernel.org, kernel-team@cloudflare•com,
Andrew Lunn <andrew+netdev@lunn•ch>,
"David S. Miller" <davem@davemloft•net>,
Eric Dumazet <edumazet@google•com>,
Alexei Starovoitov <ast@kernel•org>,
Daniel Borkmann <daniel@iogearbox•net>,
John Fastabend <john.fastabend@gmail•com>,
Stanislav Fomichev <sdf@fomichev•me>,
linux-kernel@vger•kernel.org, bpf@vger•kernel.org
Subject: Re: [PATCH net-next v5 3/5] veth: implement Byte Queue Limits (BQL) for latency reduction
Date: Sun, 10 May 2026 08:56:02 -0700 [thread overview]
Message-ID: <20260510085602.57c7a081@kernel.org> (raw)
In-Reply-To: <f459b95c-80d5-4e05-84b2-f574c92724de@kernel.org>
On Sat, 9 May 2026 11:09:51 +0200 Jesper Dangaard Brouer wrote:
> On 09/05/2026 04.06, Jakub Kicinski wrote:
> > On Thu, 7 May 2026 21:09:09 +0200 Jesper Dangaard Brouer wrote:
> >> Not against being able to modify VETH_RING_SIZE, but I don't think it is
> >> the solution here.
> >
> > Was it evaluated, tho?
> >
> > It's obviously super easy these days have AI spew no end of complex
> > code. So it'd be great to have some solid, ideally production-like
> > data to back this all up.
> >
> > VETH_RING_SIZE seems trivial, ethtool set ringparam
>
> No, unfortunately we cannot just decrease the VETH_RING_SIZE.
To be clear - I said may it configurable with ethtool -G
not change the default.
> The reason is that XDP-redirect into veth don't have any
> back-pressure and would simply drop packets if queue size becomes
> less than the NAPI budget (64). (Yes, we use both normal path and
> XDP-redirect in production).
Doesn't this mean you have a queue which is not under BQL control?
> My benchmarking shows that an optimal BQL limit is dynamically
> adjusted between 17-55 depending on veth consumer namespace
> overhead/speed, when balancing throughput and latency.
Testing with prod-approximating traffic pattern and load would be great.
next prev parent reply other threads:[~2026-05-10 15:56 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-05 13:21 [PATCH net-next v5 0/5] veth: add Byte Queue Limits (BQL) support hawk
2026-05-05 13:21 ` [PATCH net-next v5 1/5] veth: fix OOB txq access in veth_poll() with asymmetric queue counts hawk
2026-05-07 14:25 ` Paolo Abeni
2026-05-05 13:21 ` [PATCH net-next v5 2/5] net: add dev->bql flag to allow BQL sysfs for IFF_NO_QUEUE devices hawk
2026-05-05 13:21 ` [PATCH net-next v5 3/5] veth: implement Byte Queue Limits (BQL) for latency reduction hawk
2026-05-07 6:54 ` Simon Schippers
2026-05-07 13:21 ` Paolo Abeni
2026-05-07 14:34 ` Paolo Abeni
2026-05-07 14:46 ` Simon Schippers
2026-05-07 19:09 ` Jesper Dangaard Brouer
2026-05-07 20:12 ` Simon Schippers
2026-05-07 20:45 ` Jesper Dangaard Brouer
2026-05-08 8:01 ` Simon Schippers
2026-05-08 9:20 ` Simon Schippers
2026-05-09 2:06 ` Jakub Kicinski
2026-05-09 9:09 ` Jesper Dangaard Brouer
2026-05-10 15:56 ` Jakub Kicinski [this message]
2026-05-11 8:11 ` Jesper Dangaard Brouer
2026-05-11 9:55 ` Simon Schippers
2026-05-11 18:08 ` Jesper Dangaard Brouer
2026-05-11 20:37 ` Simon Schippers
2026-05-12 13:54 ` Jesper Dangaard Brouer
2026-05-12 21:55 ` Simon Schippers
2026-05-19 20:51 ` Simon Schippers
2026-05-22 7:17 ` Jonas Köppeler
[not found] ` <4ae9400a-8919-4ffc-8db3-0c334e2aa462@tu-berlin.de>
2026-05-22 8:41 ` Simon Schippers
2026-05-22 16:26 ` Jonas Köppeler
2026-05-23 16:09 ` Simon Schippers
2026-05-26 9:54 ` Jonas Köppeler
2026-05-26 14:35 ` Simon Schippers
2026-05-26 14:55 ` Jonas Köppeler
2026-05-26 15:07 ` Simon Schippers
2026-05-27 7:38 ` Jesper Dangaard Brouer
2026-05-27 7:59 ` Simon Schippers
2026-05-27 8:38 ` Simon Schippers
2026-05-05 13:21 ` [PATCH net-next v5 4/5] veth: add tx_timeout watchdog as BQL safety net hawk
2026-05-05 13:21 ` [PATCH net-next v5 5/5] net: sched: add timeout count to NETDEV WATCHDOG message hawk
2026-05-07 14:30 ` [PATCH net-next v5 0/5] veth: add Byte Queue Limits (BQL) support patchwork-bot+netdevbpf
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