From: Jakub Kicinski <kuba@kernel.org>
To: Florian Bezdeka <florian.bezdeka@siemens.com>
Cc: Maxime Chevallier <maxime.chevallier@bootlin.com>,
Andrew Lunn <andrew+netdev@lunn.ch>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Paolo Abeni <pabeni@redhat.com>,
Maxime Coquelin <mcoquelin.stm32@gmail.com>,
Alexandre Torgue <alexandre.torgue@foss.st.com>,
Yury Norov <yury.norov@gmail.com>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
Andrew Morton <akpm@linux-foundation.org>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Clark Williams <clrkwllms@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Thomas Gleixner <tglx@kernel.org>,
Jan Kiszka <jan.kiszka@siemens.com>,
netdev@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev
Subject: Re: [PATCH RFC 2/3] genirq: Honor existing IRQ affinities when setting affinity hints
Date: Thu, 20 Aug 2026 09:41:53 -0700 [thread overview]
Message-ID: <20260820094153.420202f6@kernel.org> (raw)
In-Reply-To: <20260819-flo-net-7-2-make-stmmac-default-affinity-aware-v1-2-3f79a99cadaf@siemens.com>
On Wed, 19 Aug 2026 16:30:31 +0200 Florian Bezdeka wrote:
> Some device drivers implement an IRQ balancing / spreading mechanism
> based on cpumask_local_spread() and irq_set_affinity_hint() (deprecated)
> or irq_set_affinity_and_hint().
Not an expert on IRQs, but this may make the API even more confusing.
irq_set_affinity_and_hint() not setting the affinity seems odd.
I'd go the other way and either have irq_update_affinity_hint() apply
the affinity if it's safe to do so, or create a new function for
"defaults".
Really, the drivers are dumb here, they are just trying to pass to
the core a hint which is: This is Nth of X IRQs, please spread them on
the NUMA node where the device is attached. Ideally this (Nth of X)
should even be part of request_irq() args. IRQ core already knows the
device/NUMA node. Drivers juggling multiple flavors of uAPI-shaped API
is... not very scalable. People rarely get this right.
next prev parent reply other threads:[~2026-08-20 16:42 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-19 14:30 [PATCH RFC 0/3] genirq: Allow drivers to respect userspace IRQ affinities Florian Bezdeka
2026-08-19 14:30 ` [PATCH RFC 1/3] cpumask: Honor irq_default_affinity in cpumask_local_spread() Florian Bezdeka
2026-08-19 18:38 ` Yury Norov
2026-08-20 16:09 ` Sebastian Andrzej Siewior
2026-08-20 14:30 ` sashiko-bot
2026-08-19 14:30 ` [PATCH RFC 2/3] genirq: Honor existing IRQ affinities when setting affinity hints Florian Bezdeka
2026-08-20 14:30 ` sashiko-bot
2026-08-20 16:41 ` Jakub Kicinski [this message]
2026-08-19 14:30 ` [PATCH RFC 3/3] net: stmmac: Migrate IRQ balancing to cpumask_local_spread() Florian Bezdeka
2026-08-19 18:45 ` Yury Norov
2026-08-20 14:30 ` sashiko-bot
2026-08-19 18:28 ` [PATCH RFC 0/3] genirq: Allow drivers to respect userspace IRQ affinities Yury Norov
2026-08-19 23:54 ` Andrew Lunn
2026-08-20 0:10 ` Andrew Lunn
2026-08-20 15:12 ` Sebastian Andrzej Siewior
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