linux-kernel - Re: [RFC PATCH 4/5] sched/fair: Rework inter-NUMA newidle balancing

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Message-ID: <c72802d4-7155-4c51-9d55-0372e8c4b6cb@amd.com>
Date: Thu, 10 Apr 2025 20:57:32 +0530
From: K Prateek Nayak <kprateek.nayak@....com>
To: Peter Zijlstra <peterz@...radead.org>
CC: Ingo Molnar <mingo@...hat.com>, Juri Lelli <juri.lelli@...hat.com>,
	Vincent Guittot <vincent.guittot@...aro.org>, <linux-kernel@...r.kernel.org>,
	Dietmar Eggemann <dietmar.eggemann@....com>, Steven Rostedt
	<rostedt@...dmis.org>, Ben Segall <bsegall@...gle.com>, Mel Gorman
	<mgorman@...e.de>, Valentin Schneider <vschneid@...hat.com>, "Gautham R.
 Shenoy" <gautham.shenoy@....com>, Swapnil Sapkal <swapnil.sapkal@....com>
Subject: Re: [RFC PATCH 4/5] sched/fair: Rework inter-NUMA newidle balancing

On 4/10/2025 3:44 PM, Peter Zijlstra wrote:

[..snip..]

>> +				continue;
>> +
>> +			scoped_guard (rq_lock, overloaded_rq) {
>> +				update_rq_clock(overloaded_rq);
>> +
>> +				if (!has_pushable_tasks(overloaded_rq))
>> +					break;
> 
> You can skip the clock update if there aren't any tasks to grab.

Ack.

> 
>> +
>> +				env.src_cpu = overloaded_cpu;
>> +				env.src_rq = overloaded_rq;
>> +
>> +				p = detach_one_task(&env);
> 
> Yep, detach_one_task() uses can_migrate_task() which checks
> task_on_cpu(), so that's all good :-)
> 
>> +			}
>> +
>> +			if (!p)
>> +				continue;
>> +
>> +			attach_one_task(this_rq, p);
>> +			return 1;
>> +		}
>> +
>> +		cpumask_andnot(cpus, cpus, sched_domain_span(cpu_llc));
>> +	}

-- 
Thanks and Regards,
Prateek