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From: Frederic Weisbecker <frederic@kernel.org>
To: Waiman Long <llong@redhat.com>
Cc: LKML <linux-kernel@vger.kernel.org>, Tejun Heo <tj@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Juri Lelli <juri.lelli@redhat.com>,
	Alex Belits <abelits@marvell.com>, Nitesh Lal <nilal@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Nicolas Saenz <nsaenzju@redhat.com>,
	Christoph Lameter <cl@gentwo.de>,
	Marcelo Tosatti <mtosatti@redhat.com>,
	Zefan Li <lizefan.x@bytedance.com>,
	cgroups@vger.kernel.org
Subject: Re: [RFC PATCH 0/6] cpuset: Allow to modify isolcpus through cpuset
Date: Mon, 19 Jul 2021 15:57:28 +0200	[thread overview]
Message-ID: <20210719135728.GD116346@lothringen> (raw)
In-Reply-To: <8ea7a78f-948e-75e8-1c4f-59b349c858f6@redhat.com>

On Fri, Jul 16, 2021 at 02:02:50PM -0400, Waiman Long wrote:
> On 7/14/21 9:54 AM, Frederic Weisbecker wrote:
> > The fact that "isolcpus=" behaviour can't be modified at runtime is an
> > eternal source of discussion and debate opposing a useful feature against
> > a terrible interface.
> > 
> > I've long since tried to figure out a proper way to control this at
> > runtime using cpusets, which isn't easy as a boot time single cpumask
> > is difficult to map to a hierarchy of cpusets that can even overlap.
> 
> I have a cpuset patch that allow disabling of load balancing in a cgroup-v2
> setting:
> 
> https://lore.kernel.org/lkml/20210621184924.27493-1-longman@redhat.com/
> 
> The idea of cpuset partition is that there will be no overlap of cpus in
> different partitions. So there will be no confusion whether a cpu is
> load-balanced or not.

Oh ok I missed that, time for me to check your patchset.

Thanks!

> 
> > 
> > The idea here is to map the boot-set isolation behaviour to any cpuset
> > directory whose cpumask is a subset of "isolcpus=". I let you browse
> > for details on the last patch.
> > 
> > Note this is still WIP and half-baked, but I figured it's important to
> > validate the interface early.
> 
> Using different cpumasks for different isolated properties is the easy part.
> The hard part is to make different subsystems to change their behavior as
> the isolation masks change dynamically at run time. Currently, they check
> the housekeeping cpumask only at boot time or when certain events happen.
> 
> Cheers,
> Longman
> 
> 

      reply	other threads:[~2021-07-19 13:57 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-14 13:54 Frederic Weisbecker
2021-07-14 13:54 ` [RFC PATCH 1/6] pci: Decouple HK_FLAG_WQ and HK_FLAG_DOMAIN cpumask fetch Frederic Weisbecker
2021-07-14 13:54 ` [RFC PATCH 2/6] workqueue: " Frederic Weisbecker
2021-07-14 13:54 ` [RFC PATCH 3/6] net: " Frederic Weisbecker
2021-07-14 13:54 ` [RFC PATCH 4/6] sched/isolation: Split domain housekeeping mask from the rest Frederic Weisbecker
2021-07-14 13:54 ` [RFC PATCH 5/6] sched/isolation: Make HK_FLAG_DOMAIN mutable Frederic Weisbecker
2021-07-21 14:28   ` Vincent Donnefort
2021-07-14 13:54 ` [RFC PATCH 6/6] cpuset: Add cpuset.isolation_mask file Frederic Weisbecker
2021-07-14 16:31   ` Marcelo Tosatti
2021-07-19 13:26     ` Frederic Weisbecker
2021-07-19 15:41       ` Marcelo Tosatti
2021-07-14 16:52   ` Peter Zijlstra
2021-07-14 23:13     ` Frederic Weisbecker
2021-07-14 23:44       ` Valentin Schneider
2021-07-15  0:07         ` Frederic Weisbecker
2021-07-15  9:04       ` Peter Zijlstra
2021-07-19 13:17         ` Frederic Weisbecker
2021-07-16 18:02 ` [RFC PATCH 0/6] cpuset: Allow to modify isolcpus through cpuset Waiman Long
2021-07-19 13:57   ` Frederic Weisbecker [this message]

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