From: Quentin Perret <qperret@google.com>
To: Will Deacon <will@kernel.org>
Cc: linux-arch@vger.kernel.org, Marc Zyngier <maz@kernel.org>,
kernel-team@android.com,
Vincent Guittot <vincent.guittot@linaro.org>,
Juri Lelli <juri.lelli@redhat.com>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Johannes Weiner <hannes@cmpxchg.org>,
linux-kernel@vger.kernel.org, Qais Yousef <qais.yousef@arm.com>,
Li Zefan <lizefan@huawei.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Tejun Heo <tj@kernel.org>, Suren Baghdasaryan <surenb@google.com>,
Morten Rasmussen <morten.rasmussen@arm.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v4 07/14] sched: Introduce restrict_cpus_allowed_ptr() to limit task CPU affinity
Date: Fri, 27 Nov 2020 09:49:40 +0000 [thread overview]
Message-ID: <20201127094940.GA906877@google.com> (raw)
In-Reply-To: <20201124155039.13804-8-will@kernel.org>
On Tuesday 24 Nov 2020 at 15:50:32 (+0000), Will Deacon wrote:
> Asymmetric systems may not offer the same level of userspace ISA support
> across all CPUs, meaning that some applications cannot be executed by
> some CPUs. As a concrete example, upcoming arm64 big.LITTLE designs do
> not feature support for 32-bit applications on both clusters.
>
> Although userspace can carefully manage the affinity masks for such
> tasks, one place where it is particularly problematic is execve()
> because the CPU on which the execve() is occurring may be incompatible
> with the new application image. In such a situation, it is desirable to
> restrict the affinity mask of the task and ensure that the new image is
> entered on a compatible CPU. From userspace's point of view, this looks
> the same as if the incompatible CPUs have been hotplugged off in its
> affinity mask.
>
> In preparation for restricting the affinity mask for compat tasks on
> arm64 systems without uniform support for 32-bit applications, introduce
> a restrict_cpus_allowed_ptr(), which allows the current affinity mask
> for a task to be shrunk to the intersection of a parameter mask.
>
> Signed-off-by: Will Deacon <will@kernel.org>
Reviewed-by: Quentin Perret <qperret@google.com>
Thanks,
Quentin
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next prev parent reply other threads:[~2020-11-27 9:50 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-24 15:50 [PATCH v4 00/14] An alternative series for asymmetric AArch32 systems Will Deacon
2020-11-24 15:50 ` [PATCH v4 01/14] arm64: cpuinfo: Split AArch32 registers out into a separate struct Will Deacon
2020-11-24 15:50 ` [PATCH v4 02/14] arm64: Allow mismatched 32-bit EL0 support Will Deacon
2020-11-27 10:25 ` Marc Zyngier
2020-11-27 11:50 ` Will Deacon
2020-11-27 13:09 ` Qais Yousef
2020-12-01 16:56 ` Will Deacon
2020-12-02 13:16 ` Qais Yousef
2020-11-24 15:50 ` [PATCH v4 03/14] KVM: arm64: Kill 32-bit vCPUs on systems with mismatched " Will Deacon
2020-11-27 10:26 ` Marc Zyngier
2020-11-27 11:53 ` Will Deacon
2020-11-27 17:14 ` Marc Zyngier
2020-11-27 17:24 ` Quentin Perret
2020-11-27 18:16 ` Marc Zyngier
2020-12-01 16:57 ` Will Deacon
2020-12-02 8:18 ` Marc Zyngier
2020-12-02 17:27 ` Will Deacon
2020-11-24 15:50 ` [PATCH v4 04/14] arm64: Kill 32-bit applications scheduled on 64-bit-only CPUs Will Deacon
2020-11-27 13:12 ` Qais Yousef
2020-12-01 16:56 ` Will Deacon
2020-12-02 13:52 ` Qais Yousef
2020-12-02 17:42 ` Will Deacon
2020-11-24 15:50 ` [PATCH v4 05/14] arm64: Advertise CPUs capable of running 32-bit applications in sysfs Will Deacon
2020-11-24 15:50 ` [PATCH v4 06/14] arm64: Hook up cmdline parameter to allow mismatched 32-bit EL0 Will Deacon
2020-11-27 13:17 ` Qais Yousef
2020-12-01 16:56 ` Will Deacon
2020-11-24 15:50 ` [PATCH v4 07/14] sched: Introduce restrict_cpus_allowed_ptr() to limit task CPU affinity Will Deacon
2020-11-27 9:49 ` Quentin Perret [this message]
2020-11-27 13:19 ` Qais Yousef
2020-12-01 16:56 ` Will Deacon
2020-12-02 13:06 ` Qais Yousef
2020-11-24 15:50 ` [PATCH v4 08/14] arm64: exec: Adjust affinity for compat tasks with mismatched 32-bit EL0 Will Deacon
2020-11-27 10:01 ` Quentin Perret
2020-11-27 13:23 ` Qais Yousef
2020-12-01 16:55 ` Will Deacon
2020-12-02 14:07 ` Qais Yousef
2020-11-24 15:50 ` [PATCH v4 09/14] cpuset: Don't use the cpu_possible_mask as a last resort for cgroup v1 Will Deacon
2020-11-27 13:32 ` Qais Yousef
2020-11-30 17:05 ` Qais Yousef
2020-11-30 17:36 ` Quentin Perret
2020-12-01 11:58 ` Qais Yousef
2020-12-01 12:37 ` Quentin Perret
2020-12-01 14:11 ` Qais Yousef
2020-12-01 15:56 ` Quentin Perret
2020-12-01 22:30 ` Will Deacon
2020-12-02 11:34 ` Qais Yousef
2020-12-02 11:33 ` Qais Yousef
2020-11-24 15:50 ` [PATCH v4 10/14] sched: Introduce arch_task_cpu_possible_mask() to limit fallback rq selection Will Deacon
2020-11-24 15:50 ` [PATCH v4 11/14] sched: Reject CPU affinity changes based on arch_task_cpu_possible_mask() Will Deacon
2020-11-27 9:54 ` Quentin Perret
2020-11-24 15:50 ` [PATCH v4 12/14] arm64: Prevent offlining first CPU with 32-bit EL0 on mismatched system Will Deacon
2020-11-27 13:41 ` Qais Yousef
2020-12-01 22:13 ` Will Deacon
2020-12-02 12:59 ` Qais Yousef
2020-12-02 17:42 ` Will Deacon
2020-12-02 18:08 ` Qais Yousef
2020-11-24 15:50 ` [PATCH v4 13/14] arm64: Implement arch_task_cpu_possible_mask() Will Deacon
2020-11-27 13:41 ` Qais Yousef
2020-11-24 15:50 ` [PATCH v4 14/14] arm64: Remove logic to kill 32-bit tasks on 64-bit-only cores Will Deacon
2020-11-27 13:58 ` [PATCH v4 00/14] An alternative series for asymmetric AArch32 systems Qais Yousef
2020-12-05 20:43 ` Pavel Machek
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