From: Peter Zijlstra <peterz@infradead.org> To: Waiman Long <longman@redhat.com> Cc: Tejun Heo <tj@kernel.org>, Li Zefan <lizefan@huawei.com>, Johannes Weiner <hannes@cmpxchg.org>, Ingo Molnar <mingo@redhat.com>, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, kernel-team@fb.com, pjt@google.com, luto@amacapital.net, Mike Galbraith <efault@gmx.de>, torvalds@linux-foundation.org, Roman Gushchin <guro@fb.com>, Juri Lelli <juri.lelli@redhat.com>, Patrick Bellasi <patrick.bellasi@arm.com>, Thomas Gleixner <tglx@linutronix.de> Subject: Re: [PATCH v9 3/7] cpuset: Add cpuset.sched.load_balance flag to v2 Date: Thu, 31 May 2018 18:08:57 +0200 [thread overview] Message-ID: <20180531160857.GM12180@hirez.programming.kicks-ass.net> (raw) In-Reply-To: <ebe7f0c1-b2dc-57ad-e5cb-7edf0fee4626@redhat.com> On Thu, May 31, 2018 at 11:36:39AM -0400, Waiman Long wrote: > > I'm on the fence myself; the only thing I'm fairly sure of is that tying > > this particular behaviour to the load-balance knob seems off. > > The main reason for doing it this way is that I don't want to have > load-balanced partition with no cpu in it. How about we just don't allow > consume-all at all. Each partition must have at least 1 cpu. I suspect that might be sufficient. It certainly is for the use-cases I'm aware of. You always want a system/control set which runs the regular busy work of running a system. Then you have one (or more) partitions to run your 'important' work. > > I also think we should not mix the 'consume all' thing with the > > 'fully-partitioned' thing, as they are otherwise unrelated. > > The "consume all" and "fully-partitioned" look the same to me. Are you > talking about allocating all the CPUs in a partition to sub-partitions > so that there is no CPU left in the parent partition? Not sure what you're asking. "consume all" is allowing sub-partitions to allocate all CPUs of the parent, such that there are none left. "fully-partitioned" is N cpus but no load-balancing, also equivalent to N 1 CPU parititions. They are distinct things. Disabling load-balancing should not affect how many CPUs can be allocated to sub-partitions, the moment you hit 1 CPU the load balancing is effectively off already. Going down to 0 CPUs isn't a problem for the load-balancer, it wasn't doing anything anyway. So the question is if someone really needs the one partition without balancing over N separate paritions.
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org> To: Waiman Long <longman@redhat.com> Cc: Tejun Heo <tj@kernel.org>, Li Zefan <lizefan@huawei.com>, Johannes Weiner <hannes@cmpxchg.org>, Ingo Molnar <mingo@redhat.com>, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, kernel-team@fb.com, pjt@google.com, luto@amacapital.net, Mike Galbraith <efault@gmx.de>, torvalds@linux-foundation.org, Roman Gushchin <guro@fb.com>, Juri Lelli <juri.lelli@redhat.com>, Patrick Bellasi <patrick.bellasi@arm.com>, Thomas Gleixner <tglx@linutronix.de> Subject: Re: [PATCH v9 3/7] cpuset: Add cpuset.sched.load_balance flag to v2 Date: Thu, 31 May 2018 18:08:57 +0200 [thread overview] Message-ID: <20180531160857.GM12180@hirez.programming.kicks-ass.net> (raw) In-Reply-To: <ebe7f0c1-b2dc-57ad-e5cb-7edf0fee4626@redhat.com> On Thu, May 31, 2018 at 11:36:39AM -0400, Waiman Long wrote: > > I'm on the fence myself; the only thing I'm fairly sure of is that tying > > this particular behaviour to the load-balance knob seems off. > > The main reason for doing it this way is that I don't want to have > load-balanced partition with no cpu in it. How about we just don't allow > consume-all at all. Each partition must have at least 1 cpu. I suspect that might be sufficient. It certainly is for the use-cases I'm aware of. You always want a system/control set which runs the regular busy work of running a system. Then you have one (or more) partitions to run your 'important' work. > > I also think we should not mix the 'consume all' thing with the > > 'fully-partitioned' thing, as they are otherwise unrelated. > > The "consume all" and "fully-partitioned" look the same to me. Are you > talking about allocating all the CPUs in a partition to sub-partitions > so that there is no CPU left in the parent partition? Not sure what you're asking. "consume all" is allowing sub-partitions to allocate all CPUs of the parent, such that there are none left. "fully-partitioned" is N cpus but no load-balancing, also equivalent to N 1 CPU parititions. They are distinct things. Disabling load-balancing should not affect how many CPUs can be allocated to sub-partitions, the moment you hit 1 CPU the load balancing is effectively off already. Going down to 0 CPUs isn't a problem for the load-balancer, it wasn't doing anything anyway. So the question is if someone really needs the one partition without balancing over N separate paritions. -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
next prev parent reply other threads:[~2018-05-31 16:09 UTC|newest] Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-05-29 13:41 [PATCH v9 0/7] Enable cpuset controller in default hierarchy Waiman Long 2018-05-29 13:41 ` Waiman Long 2018-05-29 13:41 ` [PATCH v9 1/7] cpuset: " Waiman Long 2018-05-29 13:41 ` Waiman Long 2018-05-29 13:41 ` [PATCH v9 2/7] cpuset: Add new v2 cpuset.sched.domain_root flag Waiman Long 2018-05-29 13:41 ` Waiman Long 2018-05-30 14:18 ` Juri Lelli 2018-05-30 14:18 ` Juri Lelli 2018-05-30 14:57 ` Waiman Long 2018-05-30 14:57 ` Waiman Long 2018-05-31 9:49 ` Peter Zijlstra 2018-05-31 9:49 ` Peter Zijlstra 2018-05-29 13:41 ` [PATCH v9 3/7] cpuset: Add cpuset.sched.load_balance flag to v2 Waiman Long 2018-05-29 13:41 ` Waiman Long 2018-05-31 10:44 ` Peter Zijlstra 2018-05-31 10:44 ` Peter Zijlstra 2018-05-31 10:54 ` Peter Zijlstra 2018-05-31 10:54 ` Peter Zijlstra 2018-05-31 13:36 ` Waiman Long 2018-05-31 13:36 ` Waiman Long 2018-05-31 12:26 ` Peter Zijlstra 2018-05-31 12:26 ` Peter Zijlstra 2018-05-31 13:54 ` Waiman Long 2018-05-31 13:54 ` Waiman Long 2018-05-31 15:20 ` Peter Zijlstra 2018-05-31 15:20 ` Peter Zijlstra 2018-05-31 15:36 ` Waiman Long 2018-05-31 15:36 ` Waiman Long 2018-05-31 16:08 ` Peter Zijlstra [this message] 2018-05-31 16:08 ` Peter Zijlstra 2018-05-31 16:42 ` Waiman Long 2018-05-31 16:42 ` Waiman Long 2018-06-20 14:46 ` Peter Zijlstra 2018-06-20 14:46 ` Peter Zijlstra 2018-06-21 7:40 ` Waiman Long 2018-06-21 7:40 ` Waiman Long 2018-05-29 13:41 ` [PATCH v9 4/7] cpuset: Make generate_sched_domains() recognize isolated_cpus Waiman Long 2018-05-29 13:41 ` Waiman Long 2018-05-29 13:41 ` [PATCH v9 5/7] cpuset: Expose cpus.effective and mems.effective on cgroup v2 root Waiman Long 2018-05-29 13:41 ` Waiman Long 2018-05-29 13:41 ` [PATCH v9 6/7] cpuset: Don't rebuild sched domains if cpu changes in non-domain root Waiman Long 2018-05-29 13:41 ` Waiman Long 2018-05-29 13:41 ` [PATCH v9 7/7] cpuset: Allow reporting of sched domain generation info Waiman Long 2018-05-29 13:41 ` Waiman Long 2018-05-30 10:13 ` [PATCH v9 0/7] Enable cpuset controller in default hierarchy Juri Lelli 2018-05-30 10:13 ` Juri Lelli 2018-05-30 12:56 ` Waiman Long 2018-05-30 12:56 ` Waiman Long 2018-05-30 13:05 ` Juri Lelli 2018-05-30 13:05 ` Juri Lelli 2018-05-30 13:47 ` Waiman Long 2018-05-30 13:47 ` Waiman Long 2018-05-30 13:52 ` Juri Lelli 2018-05-30 13:52 ` Juri Lelli
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20180531160857.GM12180@hirez.programming.kicks-ass.net \ --to=peterz@infradead.org \ --cc=cgroups@vger.kernel.org \ --cc=efault@gmx.de \ --cc=guro@fb.com \ --cc=hannes@cmpxchg.org \ --cc=juri.lelli@redhat.com \ --cc=kernel-team@fb.com \ --cc=linux-doc@vger.kernel.org \ --cc=linux-kernel@vger.kernel.org \ --cc=lizefan@huawei.com \ --cc=longman@redhat.com \ --cc=luto@amacapital.net \ --cc=mingo@redhat.com \ --cc=patrick.bellasi@arm.com \ --cc=pjt@google.com \ --cc=tglx@linutronix.de \ --cc=tj@kernel.org \ --cc=torvalds@linux-foundation.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.