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X-CSE-ConnectionGUID: uRiF5jbtTPCBFh1vN80UOw== X-CSE-MsgGUID: Cn3wuSHhTUuiveGNaSYyAQ== X-IronPort-AV: E=McAfee;i="6800,10657,11606"; a="64727949" X-IronPort-AV: E=Sophos;i="6.19,287,1754982000"; d="scan'208";a="64727949" Received: from orviesa006.jf.intel.com ([10.64.159.146]) by fmvoesa108.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Nov 2025 09:43:43 -0800 X-CSE-ConnectionGUID: 1EJ09DW9SDy2CDNTU9ZczA== X-CSE-MsgGUID: 2WHFxssfTfy1dZu+ABiNYw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.19,287,1754982000"; d="scan'208";a="187344087" Received: from schen9-mobl4.amr.corp.intel.com (HELO [10.125.111.129]) ([10.125.111.129]) by orviesa006-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Nov 2025 09:43:43 -0800 Message-ID: <4fc95e1409d3218171a54e3baaa2e2a37d724add.camel@linux.intel.com> Subject: Re: [PATCH v3] sched/fair: Skip sched_balance_running cmpxchg when balance is not due From: Tim Chen To: Shrikanth Hegde , K Prateek Nayak , Peter Zijlstra Cc: Ingo Molnar , Chen Yu , Doug Nelson , Mohini Narkhede , linux-kernel@vger.kernel.org, Vincent Guittot Date: Fri, 07 Nov 2025 09:43:42 -0800 In-Reply-To: <2edf1a85-4736-4e8b-bfc9-003dd1f34be7@linux.ibm.com> References: <52fcd1e8582a6b014a70f0ce7795ce0d88cd63a8.1762470554.git.tim.c.chen@linux.intel.com> <1d6c22aa-c882-4833-b0be-a3999d684885@amd.com> <2edf1a85-4736-4e8b-bfc9-003dd1f34be7@linux.ibm.com> Autocrypt: addr=tim.c.chen@linux.intel.com; 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charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.56.2 (3.56.2-2.fc42) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Fri, 2025-11-07 at 14:27 +0530, Shrikanth Hegde wrote: >=20 > On 11/7/25 8:27 AM, K Prateek Nayak wrote: > > Hello Tim, > >=20 > > On 11/7/2025 4:57 AM, Tim Chen wrote: > > > @@ -11757,6 +11772,7 @@ static int sched_balance_rq(int this_cpu, str= uct rq *this_rq, > > > .fbq_type =3D all, > > > .tasks =3D LIST_HEAD_INIT(env.tasks), > > > }; > > > + int need_unlock =3D false; > > > =20 > > > cpumask_and(cpus, sched_domain_span(sd), cpu_active_mask); > > > =20 > > > @@ -11768,6 +11784,13 @@ static int sched_balance_rq(int this_cpu, st= ruct rq *this_rq, > > > goto out_balanced; > > > } > > > =20 > > > + if (idle !=3D CPU_NEWLY_IDLE && (sd->flags & SD_SERIALIZE)) { >=20 > Can you also try removing "idle !=3D CPU_NEWLY_IDLE" and see the workload= behavior? > If workloads don't observe regression, it might be worth serializing it t= oo. Let me ask my colleague running OLTP to give it a try. Tim