From: Robin Murphy <robin.murphy@arm.com>
To: Thomas Gleixner <tglx@linutronix.de>,
Nitesh Lal <nilal@redhat.com>,
Jesse Brandeburg <jesse.brandeburg@intel.com>,
"frederic@kernel.org" <frederic@kernel.org>,
"juri.lelli@redhat.com" <juri.lelli@redhat.com>,
Marcelo Tosatti <mtosatti@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>,
linux-kernel@vger.kernel.org, intel-wired-lan@lists.osuosl.org,
jbrandeb@kernel.org, Alex Belits <abelits@marvell.com>,
"linux-api@vger.kernel.org" <linux-api@vger.kernel.org>,
"bhelgaas@google.com" <bhelgaas@google.com>,
"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
"rostedt@goodmis.org" <rostedt@goodmis.org>,
"peterz@infradead.org" <peterz@infradead.org>,
"davem@davemloft.net" <davem@davemloft.net>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"sfr@canb.auug.org.au" <sfr@canb.auug.org.au>,
"stephen@networkplumber.org" <stephen@networkplumber.org>,
"rppt@linux.vnet.ibm.com" <rppt@linux.vnet.ibm.com>,
"jinyuqi@huawei.com" <jinyuqi@huawei.com>,
"zhangshaokun@hisilicon.com" <zhangshaokun@hisilicon.com>,
netdev@vger.kernel.org, chris.friesen@windriver.com,
Marc Zyngier <maz@kernel.org>
Subject: Re: [PATCH tip:irq/core v1] genirq: remove auto-set of the mask when setting the hint
Date: Mon, 17 May 2021 19:50:35 +0100 [thread overview]
Message-ID: <d1d5e797-49ee-4968-88c6-c07119343492@arm.com> (raw)
In-Reply-To: <87sg2lz0zz.ffs@nanos.tec.linutronix.de>
On 2021-05-17 19:08, Thomas Gleixner wrote:
> On Mon, May 17 2021 at 18:26, Robin Murphy wrote:
>> On 2021-05-17 17:57, Nitesh Lal wrote:
>> I'm not implying that there isn't a bug, or that this code ever made
>> sense in the first place, just that fixing it will unfortunately be a
>> bit more involved than a simple revert. This patch as-is *will* subtly
>> break at least the system PMU drivers currently using
>
> s/using/abusing/
>
>> irq_set_affinity_hint() - those I know require the IRQ affinity to
>> follow whichever CPU the PMU context is bound to, in order to meet perf
>> core's assumptions about mutual exclusion.
>
> Which driver is that?
Right now, any driver which wants to control an IRQ's affinity and also
build as a module, for one thing. I'm familiar with drivers/perf/ where
a basic pattern has been widely copied; some of the callers in other
subsystems appear to *expect* it to set the underlying affinity as well,
but whether any of those added within the last 6 years represent a
functional dependency rather than just a performance concern I don't know.
Robin.
next prev parent reply other threads:[~2021-05-17 18:50 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-01 2:18 [PATCH tip:irq/core v1] genirq: remove auto-set of the mask when setting the hint Jesse Brandeburg
2021-05-04 12:15 ` Robin Murphy
2021-05-04 14:29 ` Nitesh Lal
2021-05-04 16:23 ` Jesse Brandeburg
2021-05-17 16:57 ` Nitesh Lal
2021-05-17 17:26 ` Robin Murphy
2021-05-17 18:08 ` Thomas Gleixner
2021-05-17 18:50 ` Robin Murphy [this message]
2021-05-17 19:08 ` Thomas Gleixner
2021-05-17 19:43 ` Thomas Gleixner
2021-05-17 20:18 ` Thomas Gleixner
2021-05-17 18:21 ` Nitesh Lal
2021-05-17 19:47 ` Thomas Gleixner
2021-05-17 21:13 ` Nitesh Lal
2021-05-17 20:48 ` Thomas Gleixner
2021-05-17 22:44 ` Nitesh Lal
2021-05-18 0:03 ` Thomas Gleixner
2021-05-18 0:23 ` Nitesh Lal
2021-05-20 21:57 ` Nitesh Lal
2021-05-21 0:03 ` Nitesh Lal
2021-05-21 11:56 ` Thomas Gleixner
2021-05-21 12:03 ` [PATCH] genirq: Provide new interfaces for affinity hints Thomas Gleixner
2021-05-21 15:45 ` Lijun Pan
2021-05-21 21:45 ` Thomas Gleixner
2021-05-21 16:13 ` Nitesh Lal
2021-05-21 21:48 ` Thomas Gleixner
2021-06-04 20:35 ` Nitesh Lal
2021-05-27 10:03 ` Shung-Hsi Yu
2021-05-27 10:21 ` Shung-Hsi Yu
2021-05-27 13:06 ` Nitesh Lal
2021-05-28 7:20 ` Shung-Hsi Yu
2021-06-07 17:00 ` Nitesh Lal
2021-06-14 16:12 ` Nitesh Lal
2021-05-21 13:46 ` [PATCH tip:irq/core v1] genirq: remove auto-set of the mask when setting the hint Nitesh Lal
2021-05-21 15:15 ` Thomas Gleixner
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