From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8169B189F20 for ; Fri, 25 Apr 2025 16:05:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.163.156.1 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745597135; cv=none; b=LqxXue+jBEZMgLwYgSW70M3LhR/Qtxklj7ag4/b/cj4QuiLNIHnOJCND0arDwPR/5V7ERrjqmKZnCUMv+y8PgOc0Qjm8hxQhJj8O/CtJJUoyZ3vQo9vQieWw/OWW5uFLeIdkN1v00EnEIkXW6hVXeShk0H9F+iP1sgOsecqE+u4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745597135; c=relaxed/simple; bh=5QOikvIpFJpAn4LvksqDdxME5NqzJU/6HMKXaTAmFIk=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=VqeBqYa4P7g3FW9xhfJp9573xxw6GEwZBy0xZYrplNO3rna0dQVIVCuPfF9zpsClYcyv6Yb3g2DXNoPM6diYF9cmWNeKZkgKWO3jvv3hfRvmeyLI4lYKiIrgoJQDwJVFpwjbu3/jtU+GR58Gs6r1UN3FHP2GxczkbVad/IKJg1o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com; spf=pass smtp.mailfrom=linux.ibm.com; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b=RgbPxNwX; arc=none smtp.client-ip=148.163.156.1 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b="RgbPxNwX" Received: from pps.filterd (m0353729.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.18.1.2/8.18.1.2) with ESMTP id 53PAEckf001860; Fri, 25 Apr 2025 16:05:18 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=cc :content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to; s=pp1; bh=OVBNyZ RHCPpzSSHMY3VqwIMIHRvAFKA2l4bEjmWWMXM=; b=RgbPxNwXUuPGznwiP9fwp2 D+AMO2pty/kC6gAIorfkkQyAEJCkUaFCdYqtlX7ZTJC0YfY1JbjP/OOPzWK/IoPP s9bpgKVXnrFM9lvQgsP3l6p/ikhwEcSi0HZzVnOl4SbrrWEJoFXASaIGjgC4wySX 00pb5iaj1N9Teer995rHhMFrRL9s5drpq2mGNLYZcAcxaazG5464/HxfG/b5RSz2 D3WvZ3ASJFXcEydSCg+ijb6k6e1hprUYWYJhUQ0J9etFHTlYGl46mj8iT0WndUz7 ZTv35FLRSlcN3mt4tPZQRjlW9rt9PcFAhXPZYVzNCvfJiVscdGbDSGjWitN7ThVw == Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 467vvkveh4-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 25 Apr 2025 16:05:17 +0000 (GMT) Received: from m0353729.ppops.net (m0353729.ppops.net [127.0.0.1]) by pps.reinject (8.18.0.8/8.18.0.8) with ESMTP id 53PG5HwW027221; Fri, 25 Apr 2025 16:05:17 GMT Received: from ppma22.wdc07v.mail.ibm.com (5c.69.3da9.ip4.static.sl-reverse.com [169.61.105.92]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 467vvkveh2-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 25 Apr 2025 16:05:17 +0000 (GMT) Received: from pps.filterd (ppma22.wdc07v.mail.ibm.com [127.0.0.1]) by ppma22.wdc07v.mail.ibm.com (8.18.1.2/8.18.1.2) with ESMTP id 53PCvo4G005884; Fri, 25 Apr 2025 16:05:16 GMT Received: from smtprelay05.fra02v.mail.ibm.com ([9.218.2.225]) by ppma22.wdc07v.mail.ibm.com (PPS) with ESMTPS id 466jfxp0p5-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 25 Apr 2025 16:05:16 +0000 Received: from smtpav02.fra02v.mail.ibm.com (smtpav02.fra02v.mail.ibm.com [10.20.54.101]) by smtprelay05.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 53PG5EJg56885648 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 25 Apr 2025 16:05:14 GMT Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 184DB2004B; Fri, 25 Apr 2025 16:05:14 +0000 (GMT) Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 0E93720043; Fri, 25 Apr 2025 16:05:11 +0000 (GMT) Received: from [9.124.216.146] (unknown [9.124.216.146]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTP; Fri, 25 Apr 2025 16:05:10 +0000 (GMT) Message-ID: <895d688d-64aa-4321-9978-8773e726aee2@linux.ibm.com> Date: Fri, 25 Apr 2025 21:35:10 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] sched/fair: reduce false sharing on sched_balance_running To: Eric Dumazet Cc: linux-kernel , Eric Dumazet , Yafang Shao , Sean Christopherson , Josh Don , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider References: <20250423174634.3009657-1-edumazet@google.com> From: Shrikanth Hegde Content-Language: en-US In-Reply-To: <20250423174634.3009657-1-edumazet@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwNDI1MDExMSBTYWx0ZWRfX16njmbsy1kK8 p0b+MZ3Ez0sim1kt7GZLc/VIK8RUqd0zMBdRH0zizo8wdhWvB53Ro21znWOYhNkHsxPCNlQ1uul Fmq15T1bBl3eagQPnZNcAzDaaeU0m41pls0srRHTIJeF0QZnPcijKipzMcrkkq3H48koid+m/vZ DeCmSOf1ln6LQ3bUf+jo3wn32ZCBbhvCbqB+AXskMTe8Y9Jd1tikb5o1NygOp8x06GTYRMy0t+7 WvvT4UH4JjTII2lrBYJ44buvMpYWm8lQuNUueg5mlLHU14Ly2Rys2BjxflSQ5iGOIMXmRJRva0a +eJUgb76yxy4Sr4tBh6gRZHpIcedPXxDw2vk6GJyXV2CW1EJQKFJGFR5gae0nc8DFN/CtmteYch Wc3uu0VjxMNlI9Xwh7d98Iu8VloWfv5s6WRHRnmOpJykh6A05JU0AVpl4xSh7ZmLpC7rXPAJ X-Proofpoint-ORIG-GUID: IFZmFdJrWV6Iu1uVoe2fmKOy4tx1YNYn X-Proofpoint-GUID: kppcrlXmEiPooCRtiMmdjiuPn2uMrhlA X-Authority-Analysis: v=2.4 cv=HoF2G1TS c=1 sm=1 tr=0 ts=680bb2bd cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=IkcTkHD0fZMA:10 a=XR8D0OoHHMoA:10 a=VwQbUJbxAAAA:8 a=QyXUC8HyAAAA:8 a=VnNF1IyMAAAA:8 a=1XWaLZrsAAAA:8 a=pGLkceISAAAA:8 a=JeRp_uJUotQMxpzSFH4A:9 a=QEXdDO2ut3YA:10 a=ZXulRonScM0A:10 a=zZCYzV9kfG8A:10 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.0.736,FMLib:17.12.80.40 definitions=2025-04-25_04,2025-04-24_02,2025-02-21_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxlogscore=812 lowpriorityscore=0 phishscore=0 clxscore=1015 impostorscore=0 adultscore=0 bulkscore=0 suspectscore=0 priorityscore=1501 malwarescore=0 mlxscore=0 spamscore=0 classifier=spam authscore=0 authtc=n/a authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2504070000 definitions=main-2504250111 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 > Cc: Yafang Shao > Cc: Sean Christopherson > Cc: Josh Don > --- 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