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From: Shrikanth Hegde <sshegde@linux.ibm.com>
To: Eric Dumazet <edumazet@google.com>
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
	Eric Dumazet <eric.dumazet@gmail.com>,
	Yafang Shao <laoar.shao@gmail.com>,
	Sean Christopherson <seanjc@google.com>,
	Josh Don <joshdon@google.com>, Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Juri Lelli <juri.lelli@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
	Valentin Schneider <vschneid@redhat.com>
Subject: Re: [PATCH] sched/fair: reduce false sharing on sched_balance_running
Date: Fri, 25 Apr 2025 21:35:10 +0530	[thread overview]
Message-ID: <895d688d-64aa-4321-9978-8773e726aee2@linux.ibm.com> (raw)
In-Reply-To: <20250423174634.3009657-1-edumazet@google.com>



On 4/23/25 23:16, Eric Dumazet wrote:
> rebalance_domains() can attempt to change sched_balance_running
> more than 350,000 times per second on our servers.
> 
> If sched_clock_irqtime and sched_balance_running share the
> same cache line, we see a very high cost on hosts with 480 threads
> dealing with many interrupts.
> 
> This patch only acquires sched_balance_running when sd->last_balance
> is old enough.
> 
> It also moves sched_balance_running into a dedicated cache line on SMP.
> 
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Cc: Yafang Shao <laoar.shao@gmail.com>
> Cc: Sean Christopherson <seanjc@google.com>
> Cc: Josh Don <joshdon@google.com>
> ---

Hi Eric.

Please check this thread which does the same thing AFAIU.
https://lore.kernel.org/all/20250416035823.1846307-1-tim.c.chen@linux.intel.com/

You could also try:
https://lore.kernel.org/all/82baaf6c-f3d9-4c3e-be69-24389eadb18c@linux.ibm.com/

Thanks


  parent reply	other threads:[~2025-04-25 16:05 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-04-23 17:46 Eric Dumazet
2025-04-24 14:45 ` Yafang Shao
2025-04-24 15:49   ` Eric Dumazet
2025-04-25  2:29     ` Yafang Shao
2025-04-25 16:22       ` Eric Dumazet
2025-04-26 10:43         ` Yafang Shao
2025-04-24 20:06 ` Josh Don
2025-04-25 16:05 ` Shrikanth Hegde [this message]
2025-04-25 16:14   ` Eric Dumazet

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