From: Qais Yousef <qais.yousef@arm.com>
To: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: linux-arch@vger.kernel.org, Marc Zyngier <maz@kernel.org>,
"Peter Zijlstra \(Intel\)" <peterz@infradead.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
James Morse <james.morse@arm.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Will Deacon <will@kernel.org>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [RFC PATCH v2 4/4] arm64: Export id_aar64fpr0 via sysfs
Date: Wed, 21 Oct 2020 15:31:53 +0100 [thread overview]
Message-ID: <20201021143153.7ef7n7gdd42l4rbc@e107158-lin> (raw)
In-Reply-To: <20201021133316.GF8004@e123083-lin>
On 10/21/20 15:33, Morten Rasmussen wrote:
> On Wed, Oct 21, 2020 at 01:15:59PM +0100, Catalin Marinas wrote:
> > one, though not as easy as automatic task placement by the scheduler (my
> > first preference, followed by the id_* regs and the aarch32 mask, though
> > not a strong preference for any).
>
> Automatic task placement by the scheduler would mean giving up the
> requirement that the user-space affinity mask must always be honoured.
> Is that on the table?
>
> Killing aarch32 tasks with an empty intersection between the user-space
> mask and aarch32_mask is not really "automatic" and would require the
> aarch32 capability to be exposed anyway.
I just noticed this nasty corner case too.
Documentation/admin-guide/cgroup-v1/cpusets.rst: Section 1.9
"If such a task had been bound to some subset of its cpuset using the
sched_setaffinity() call, the task will be allowed to run on any CPU allowed in
its new cpuset, negating the effect of the prior sched_setaffinity() call."
So user space must put the tasks into a valid cpuset to fix the problem. Or
make the scheduler behave like the affinity is associated with a cpuset.
Can user space put the task into the correct cpuset without a race? Clone3
syscall learnt to specify a cgroup to attach to when forking. Should we do the
same for execve()?
Thanks
--
Qais Yousef
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next prev parent reply other threads:[~2020-10-21 14:33 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-21 10:46 [RFC PATCH v2 0/4] Add support for Asymmetric AArch32 systems Qais Yousef
2020-10-21 10:46 ` [RFC PATCH v2 1/4] arm64: kvm: Handle " Qais Yousef
2020-10-21 12:02 ` Marc Zyngier
2020-10-21 13:35 ` Qais Yousef
2020-10-21 13:51 ` Marc Zyngier
2020-10-21 14:38 ` Qais Yousef
2020-11-02 17:58 ` Qais Yousef
2020-10-21 10:46 ` [RFC PATCH v2 2/4] arm64: Add support for asymmetric AArch32 EL0 configurations Qais Yousef
2020-10-21 15:39 ` Will Deacon
2020-10-21 16:21 ` Qais Yousef
2020-10-21 16:52 ` Catalin Marinas
2020-10-21 17:39 ` Will Deacon
2020-10-22 9:53 ` Catalin Marinas
2020-10-21 10:46 ` [RFC PATCH v2 3/4] arm64: export emulate_sys_reg() Qais Yousef
2020-10-21 10:46 ` [RFC PATCH v2 4/4] arm64: Export id_aar64fpr0 via sysfs Qais Yousef
2020-10-21 11:09 ` Marc Zyngier
2020-10-21 11:25 ` Greg Kroah-Hartman
2020-10-21 11:46 ` Marc Zyngier
2020-10-21 12:11 ` Greg Kroah-Hartman
2020-10-21 13:18 ` Qais Yousef
2020-10-21 12:15 ` Catalin Marinas
2020-10-21 13:20 ` Qais Yousef
2020-10-21 13:33 ` Morten Rasmussen
2020-10-21 14:09 ` Catalin Marinas
2020-10-21 14:41 ` Morten Rasmussen
2020-10-21 14:45 ` Will Deacon
2020-10-21 15:10 ` Catalin Marinas
2020-10-21 15:37 ` Will Deacon
2020-10-21 16:18 ` Catalin Marinas
2020-10-21 17:19 ` Will Deacon
2020-10-22 9:55 ` Morten Rasmussen
2020-10-21 14:31 ` Qais Yousef [this message]
2020-10-22 10:16 ` Morten Rasmussen
2020-10-22 10:48 ` Qais Yousef
2020-10-21 14:41 ` Will Deacon
2020-10-21 15:03 ` Qais Yousef
2020-10-21 15:23 ` Will Deacon
2020-10-21 16:07 ` Qais Yousef
2020-10-21 17:23 ` Will Deacon
2020-10-21 19:57 ` Qais Yousef
2020-10-21 20:26 ` Will Deacon
2020-10-22 8:16 ` Catalin Marinas
2020-10-22 9:58 ` Qais Yousef
2020-10-22 13:47 ` Qais Yousef
2020-10-22 13:55 ` Greg Kroah-Hartman
2020-10-22 14:31 ` Catalin Marinas
2020-10-22 14:34 ` Qais Yousef
2020-10-26 19:02 ` Qais Yousef
2020-10-26 19:08 ` Greg Kroah-Hartman
2020-10-26 19:18 ` Qais Yousef
2020-10-21 11:28 ` Greg Kroah-Hartman
2020-10-21 13:22 ` Qais Yousef
2020-10-21 11:26 ` [RFC PATCH v2 0/4] Add support for Asymmetric AArch32 systems Greg Kroah-Hartman
2020-10-21 13:15 ` Qais Yousef
2020-10-21 13:31 ` Greg Kroah-Hartman
2020-10-21 13:55 ` Qais Yousef
2020-10-21 14:35 ` Catalin Marinas
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