From: "Michael S. Tsirkin" <mst@redhat.com>
To: Simon Schippers <simon.schippers@tu-dortmund.de>
Cc: Jason Wang <jasowang@redhat.com>,
willemdebruijn.kernel@gmail.com, andrew+netdev@lunn.ch,
davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
pabeni@redhat.com, eperezma@redhat.com, leiyang@redhat.com,
stephen@networkplumber.org, jon@nutanix.com,
tim.gebauer@tu-dortmund.de, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
virtualization@lists.linux.dev
Subject: Re: [PATCH net-next v7 3/9] tun/tap: add ptr_ring consume helper with netdev queue wakeup
Date: Sat, 14 Feb 2026 13:18:41 -0500 [thread overview]
Message-ID: <20260214131703-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <59529fd2-2a08-4a89-a853-27198b76f842@tu-dortmund.de>
On Sat, Feb 14, 2026 at 06:13:14PM +0100, Simon Schippers wrote:
...
> Patched: Waking on __ptr_ring_produce_created_space() is too early. The
> stop/wake cycle occurs too frequently which slows down
> performance as can be seen for TAP.
>
> Wake on empty variant: Waking on __ptr_ring_empty() is (slightly) too
> late. The consumer starves because the producer
> first has to produce packets again. This slows
> down performance aswell as can be seen for TAP
> and TAP+vhost-net (both down ~30-40Kpps).
>
> I think something inbetween should be used.
> The wake should be done as late as possible to have as few
> NET_TX_SOFTIRQs as possible but early enough that there are still
> consumable packets remaining to not starve the consumer.
>
> However, I can not think of a proper way to implement this right now.
>
> Thanks!
What is the difficulty?
Your patches check __ptr_ring_consume_created_space(..., 1).
How about __ptr_ring_consume_created_space(..., 8) then? 16?
--
MST
next prev parent reply other threads:[~2026-02-14 18:18 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-07 21:04 [PATCH net-next v7 0/9] tun/tap & vhost-net: apply qdisc backpressure on full ptr_ring to reduce TX drops Simon Schippers
2026-01-07 21:04 ` [PATCH net-next v7 1/9] ptr_ring: move free-space check into separate helper Simon Schippers
2026-01-07 21:04 ` [PATCH net-next v7 2/9] ptr_ring: add helper to detect newly freed space on consume Simon Schippers
2026-01-08 3:23 ` Jason Wang
2026-01-08 7:20 ` Simon Schippers
2026-01-09 6:01 ` Jason Wang
2026-01-09 6:47 ` Michael S. Tsirkin
2026-01-09 7:22 ` Michael S. Tsirkin
2026-01-09 7:35 ` Simon Schippers
2026-01-09 8:31 ` Michael S. Tsirkin
2026-01-09 9:06 ` Simon Schippers
2026-01-12 16:29 ` Simon Schippers
2026-01-07 21:04 ` [PATCH net-next v7 3/9] tun/tap: add ptr_ring consume helper with netdev queue wakeup Simon Schippers
2026-01-08 3:38 ` Jason Wang
2026-01-08 7:40 ` Simon Schippers
2026-01-09 6:02 ` Jason Wang
2026-01-09 9:31 ` Simon Schippers
2026-01-21 9:32 ` Simon Schippers
2026-01-22 5:35 ` Jason Wang
2026-01-23 3:05 ` Jason Wang
2026-01-23 9:54 ` Simon Schippers
2026-01-27 16:47 ` Simon Schippers
2026-01-28 7:03 ` Jason Wang
2026-01-28 7:53 ` Simon Schippers
2026-01-29 1:14 ` Jason Wang
2026-01-29 9:24 ` Simon Schippers
2026-01-30 1:51 ` Jason Wang
2026-02-01 20:19 ` Simon Schippers
2026-02-03 3:48 ` Jason Wang
2026-02-04 15:43 ` Simon Schippers
2026-02-05 3:59 ` Jason Wang
2026-02-05 22:28 ` Simon Schippers
2026-02-06 3:21 ` Jason Wang
2026-02-08 18:18 ` Simon Schippers
2026-02-12 0:12 ` Simon Schippers
2026-02-12 7:06 ` Michael S. Tsirkin
2026-02-12 8:03 ` Simon Schippers
2026-02-12 8:14 ` Jason Wang
2026-02-14 17:13 ` Simon Schippers
2026-02-14 18:18 ` Michael S. Tsirkin [this message]
2026-02-14 19:51 ` Simon Schippers
2026-02-14 23:49 ` Michael S. Tsirkin
2026-02-15 10:38 ` Michael S. Tsirkin
2026-02-16 13:27 ` Simon Schippers
2026-01-07 21:04 ` [PATCH net-next v7 4/9] tun/tap: add batched ptr_ring consume functions " Simon Schippers
2026-01-07 21:04 ` [PATCH net-next v7 5/9] tun/tap: add unconsume function for returning entries to ptr_ring Simon Schippers
2026-01-08 3:40 ` Jason Wang
2026-01-07 21:04 ` [PATCH net-next v7 6/9] tun/tap: add helper functions to check file type Simon Schippers
2026-01-07 21:04 ` [PATCH net-next v7 7/9] vhost-net: vhost-net: replace rx_ring with tun/tap ring wrappers Simon Schippers
2026-01-08 4:38 ` Jason Wang
2026-01-08 7:47 ` Simon Schippers
2026-01-09 6:04 ` Jason Wang
2026-01-09 9:57 ` Simon Schippers
2026-01-12 2:54 ` Jason Wang
2026-01-12 4:42 ` Michael S. Tsirkin
2026-01-07 21:04 ` [PATCH net-next v7 8/9] tun/tap: drop get ring exports Simon Schippers
2026-01-07 21:04 ` [PATCH net-next v7 9/9] tun/tap & vhost-net: avoid ptr_ring tail-drop when qdisc is present Simon Schippers
2026-01-08 4:37 ` Jason Wang
2026-01-08 8:01 ` Simon Schippers
2026-01-09 6:09 ` Jason Wang
2026-01-09 10:14 ` Simon Schippers
2026-01-12 2:22 ` Jason Wang
2026-01-12 11:08 ` Simon Schippers
2026-01-12 11:18 ` Michael S. Tsirkin
2026-01-13 6:26 ` Jason Wang
2026-01-12 4:33 ` Michael S. Tsirkin
2026-01-12 11:17 ` Simon Schippers
2026-01-12 11:19 ` Michael S. Tsirkin
2026-01-12 11:28 ` Simon Schippers
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