From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: linux-kernel@vger.kernel.org, netdev@vger.kernel.org
Cc: "David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Wander Lairson Costa <hawk@kernel.org>
Subject: [PATCH net-next 0/2] net: Use SMP threads for backlog NAPI (or optional).
Date: Fri, 29 Sep 2023 18:20:18 +0200 [thread overview]
Message-ID: <20230929162121.1822900-1-bigeasy@linutronix.de> (raw)
The RPS code and "deferred skb free" both send IPI/ function call
to a remote CPU in which a softirq is raised. This leads to a warning on
PREEMPT_RT because raising softiqrs from function call led to undesired
behaviour in the past. I had duct tape in RT for the "deferred skb free"
and Wander Lairson Costa reported the RPS case.
Changes:
- RFC…v1 https://lore.kernel.org/all/20230818092111.5d86e351@kernel.org
- Patch #2 has been removed. Removing the warning is still an option.
- There are two patches in the series:
- Patch #1 always creates backlog threads
- Patch #2 creates the backlog threads if requested at boot time,
mandatory on PREEMPT_RT.
So it is either or and I wanted to show how both look like.
- The kernel test robot reported a performance regression with
loopback (stress-ng --udp X --udp-ops Y) against the RFC version.
The regression is now avoided by using local-NAPI if backlog
processing is requested on the local CPU.
Sebastian
next reply other threads:[~2023-09-29 16:21 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-29 16:20 Sebastian Andrzej Siewior [this message]
2023-09-29 16:20 ` [PATCH net-next 1/2] net: Use SMP threads for backlog NAPI Sebastian Andrzej Siewior
2023-09-29 16:20 ` [PATCH net-next 2/2] net: Allow to use " Sebastian Andrzej Siewior
2023-10-04 22:46 ` [PATCH net-next 0/2] net: Use SMP threads for backlog NAPI (or optional) Jakub Kicinski
2023-10-07 15:59 ` Sebastian Andrzej Siewior
2023-10-10 1:09 ` Jakub Kicinski
2023-10-16 9:53 ` Sebastian Andrzej Siewior
2023-10-16 14:17 ` Jakub Kicinski
2023-10-16 14:53 ` Sebastian Andrzej Siewior
2023-10-31 10:14 ` Sebastian Andrzej Siewior
2023-10-31 11:36 ` Wander Lairson Costa
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