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From: "Michal Koutný" <mkoutny@suse.com>
To: Waiman Long <longman@redhat.com>
Cc: Frederic Weisbecker <frederic@kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Roman Gushchin <roman.gushchin@linux.dev>,
	Michal Hocko <mhocko@suse.com>,
	Marcelo Tosatti <mtosatti@redhat.com>,
	Leonardo <leobras@redhat.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Shakeel Butt <shakeelb@google.com>,
	Muchun Song <muchun.song@linux.dev>,
	Andrew Morton <akpm@linux-foundation.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	cgroups@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 2/2] sched/isolation: Add cpu_is_isolated() API
Date: Mon, 6 Feb 2023 16:47:10 +0100	[thread overview]
Message-ID: <20230206154710.GC21332@blackbody.suse.cz> (raw)
In-Reply-To: <0f388863-9498-e61e-e2dc-965654544489@redhat.com>

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Hello.

On Fri, Feb 03, 2023 at 10:53:46PM -0500, Waiman Long <longman@redhat.com> wrote:
> CPUs in an isolated cpuset partition is similar to HK_TYPE_DOMAIN CPUs as
> load balancing is disabled. I can add an API to access the cpumask and add
> to this API. However, that list is dynamic as it can be changed at run time.
> Will that be a problem?

I can see a problem already -- as a CPU can be dynamically switched to
"isolated" mode so should all dependent operations support that (switch)
too, i.e. the CPUs local PCP caches would have to be drained when the
CPU enters isolation.

> Or should that be used separately?

It'd be nice to have both (cpuset and cmdline flags) eventually unified.

Alas, it only leads me conservatively to:

#ifndef CONFIG_CPUSETS
// the proposed implementaion
else
static inline bool cpu_is_isolated(int cpu) {
	return true;
}
#endif

My 0.02€,
Michal


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  reply	other threads:[~2023-02-06 15:47 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-02-03 23:24 [PATCH 0/2] sched/isolation: Prep work for pcp cache draining isolation Frederic Weisbecker
2023-02-03 23:24 ` [PATCH 1/2] sched/isolation: Merge individual nohz_full features into a common housekeeping flag Frederic Weisbecker
2023-02-06 15:51   ` Michal Koutný
2023-02-07 11:49     ` Frederic Weisbecker
2023-02-07 12:59       ` Michal Koutný
2023-02-07 15:21         ` Waiman Long
2023-02-03 23:24 ` [PATCH 2/2] sched/isolation: Add cpu_is_isolated() API Frederic Weisbecker
2023-02-04  3:53   ` Waiman Long
2023-02-06 15:47     ` Michal Koutný [this message]
2023-02-06 16:50       ` Waiman Long
2023-02-07 12:16     ` Frederic Weisbecker
2023-02-04 11:09   ` kernel test robot
2023-02-05  5:47   ` kernel test robot
2023-02-13 13:34   ` Michal Hocko

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