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Shenoy" , Swapnil Sapkal , Shrikanth Hegde , Chen Yu Subject: [RESEND RFC PATCH v2 16/29] sched/topology: Introduce "nohz_idle_cpus_mask" in sd->shared Date: Mon, 8 Dec 2025 09:27:02 +0000 Message-ID: <20251208092744.32737-16-kprateek.nayak@amd.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20251208083602.31898-1-kprateek.nayak@amd.com> References: <20251208083602.31898-1-kprateek.nayak@amd.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: satlexmb07.amd.com (10.181.42.216) To satlexmb07.amd.com (10.181.42.216) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS3PEPF0000C37B:EE_|DS0PR12MB6464:EE_ X-MS-Office365-Filtering-Correlation-Id: c890fc0b-c79f-4916-bd0b-08de363cb2da X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|36860700013|7416014|1800799024|376014|82310400026; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?Xv9vPC04Hehafk2vjgtczsnVNGb9vhY59lAQhJXSlS00jUPiewOaIWfou6sg?= =?us-ascii?Q?FwFlg4wVX5BoTWrjoMopX0p7QyXLhA18SZkHq5r9BynjOFW0K17GSdqlfHmP?= =?us-ascii?Q?KWni/7XZ1sESKw42vpGTCOysxJEED29sPxae8P/rM4dHmGFrtCqCE2G1hK1F?= =?us-ascii?Q?xkYILe703wESsgsfpCeXvbWRedYfFGb/SMtHyhzEGk0xP+BdTKYbNZqnyxyn?= =?us-ascii?Q?1lpJnhFb0PMFHst3PjvUzY8CV+BoECprn2ZL/mWFSHfALzLcxC3fUcR8XE0l?= =?us-ascii?Q?Xd0PplSkAm4aTwlr5SC9R9e+Xf8eFpW1q0twLPq1Au85DevH/HiAx2ZYlAht?= =?us-ascii?Q?hp4DonwpnDP62FRn71XKQF3cWEFY6jqM3SGo/Mod/OfRpMLbKgAEGnzIjtsB?= =?us-ascii?Q?4RLq1/27TW7cxSfSi5KuCj4IaypNHZliIBKZRproSwtxdagKUz0G1tNilHrH?= =?us-ascii?Q?Ws05N5KtfkQ6rWautr5wlTmU5e3eH20SwRlDmPAhmsHbJ1hnaNEMKvUQtH0K?= =?us-ascii?Q?sst03NDmQF2tv3EB+aSqUHw1iEAE3nubhITEudu/W7V+TaFjuZNSIsBFa8vd?= =?us-ascii?Q?YJF6m97cjgwOHuP5WJ6SQTowehx+yTTs8GNg2UjkKBiQH+aIqi7sAuY3u7mP?= =?us-ascii?Q?JqxU1f3WVkUPmIDnpvLP61bjhyEuwMjtmeoc4QuVR82BcFEoGosA10UU858K?= =?us-ascii?Q?tVMA4JGt/0+Ao9nepS1hnX9i0ARHiNd5fLF90YJiLM7Z792Zv6v640n0g3B1?= =?us-ascii?Q?aTYj31yVJgvc2HGRjwNnt1FQeTWDnKLvcGWqOp4oQ1LhiMbat9ZUl+Fhqvmz?= =?us-ascii?Q?XLWDuaDgMh4cHw2iMpXG491fMc3XNQu90rlMoe5ztG0B1/rRkt6KpUbJjjG3?= =?us-ascii?Q?aeXuV9SMr2oe9Qo1O4D116Ko4JUlpEjM1Wc3dJXS7iHYkV8bNxUVF+W7sYaQ?= =?us-ascii?Q?cyoqw+t+4EWZ5Mx/ahnoKYpqBvOPKyPwdLpgqtu1V4BCCDg0a25bwcPxVOWi?= =?us-ascii?Q?0LGYMFGJWKTGNGKKVpELLnASTDAWu0eTOHsvg3TejT9AY+zho2QEen+gV7Td?= =?us-ascii?Q?5CgHqpOSBMwr0uhcf/Omm+pjj/Zvzlj9EWGBZRbvg7dtpGXDAkpUwFKDSjpQ?= =?us-ascii?Q?HU9JUDixk6DdysVzeRs9y1XNR0ybJEuLfMsNsoNENTN2t34mWI124jYtDjRc?= =?us-ascii?Q?+WA/HQAzdtPfL8ueT+dX+vnz0smuyD5uc0Ex38JSgMZZJJVAdgmUfbCAkPfU?= =?us-ascii?Q?s4STyw0VWc06KnSoB2/pn//mbI/xgo6jQLVCQrQDxrtmQpWnuDX3M37jjvK6?= =?us-ascii?Q?EcOy6uDSZFY95wElK/lySL/sXoSjpX4bGYdlnLbZE8mMe50uDjNJb0WYK4Lm?= =?us-ascii?Q?qFzF67bI50tHd7U4CYT708YhU7pbd32pKPjSvnXvl2AyUYdSHzsqWMh/hnk8?= =?us-ascii?Q?n8Cc+sY+oOqgbrfVqt1maX2gNlvGGLlNAFA2Ascesc4R1gq/Hm3sIaZtPU6V?= =?us-ascii?Q?ncfFc7L961pct1Qxfdpw1mqyjkBOR46C8teCcWPtQ6P0qwNglDHctW+YS5/8?= =?us-ascii?Q?fjuWYA2D3hhbEyxzQ4E=3D?= X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:satlexmb07.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(36860700013)(7416014)(1800799024)(376014)(82310400026);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 08 Dec 2025 09:32:25.9067 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: c890fc0b-c79f-4916-bd0b-08de363cb2da X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[satlexmb07.amd.com] X-MS-Exchange-CrossTenant-AuthSource: DS3PEPF0000C37B.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS0PR12MB6464 Content-Type: text/plain; charset="utf-8" Introduce "nohz_idle_cpus_mask" to track idle CPUs within the sd_nohz domains. This mask will eventually replace the need for the global "nohz.idle_cpus" mask for nohz idle balancing. Convert cpu_set_sd_state_*() to set / clear the CPU from the mask when transitioning to / out of nohz idle state. Reviewed-by: Gautham R. Shenoy Signed-off-by: K Prateek Nayak --- include/linux/sched/topology.h | 1 + kernel/sched/fair.c | 2 ++ kernel/sched/topology.c | 48 +++++++++++++++++++++++++++++++--- 3 files changed, 47 insertions(+), 4 deletions(-) diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h index 15c61aed1b5c..280915ff7acf 100644 --- a/include/linux/sched/topology.h +++ b/include/linux/sched/topology.h @@ -67,6 +67,7 @@ struct sched_domain_shared { atomic_t ref; #ifdef CONFIG_NO_HZ_COMMON atomic_t nr_idle_cpus; + struct cpumask *nohz_idle_cpus_mask; #endif int has_idle_cores; int nr_idle_scan; diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index be7e818687c7..8f21b655fc40 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -12562,6 +12562,7 @@ static void set_cpu_sd_state_busy(int cpu) if (!xchg(&sd->nohz_idle, 0)) return; =20 + cpumask_clear_cpu(cpu, sd->shared->nohz_idle_cpus_mask); atomic_dec(&sd->shared->nr_idle_cpus); } =20 @@ -12592,6 +12593,7 @@ static void set_cpu_sd_state_idle(int cpu) if (xchg(&sd->nohz_idle, 1)) return; =20 + cpumask_set_cpu(cpu, sd->shared->nohz_idle_cpus_mask); atomic_inc(&sd->shared->nr_idle_cpus); } =20 diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index 5c399ca1f4a1..59089ed3b840 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -468,6 +468,24 @@ struct s_data { =20 DEFINE_PER_CPU(struct sched_domain __rcu *, sd_nohz); =20 +static int __sds_nohz_idle_alloc(struct sched_domain_shared *sds, int node) +{ + sds->nohz_idle_cpus_mask =3D kzalloc_node(cpumask_size(), GFP_KERNEL, nod= e); + + if (!sds->nohz_idle_cpus_mask) + return -ENOMEM; + + return 0; +} + +static void __sds_nohz_idle_free(struct sched_domain_shared *sds) +{ + if (!sds) + return; + + kfree(sds->nohz_idle_cpus_mask); +} + static int __fallback_sds_alloc(struct s_data *d, unsigned long *visited_n= odes) { int j; @@ -490,6 +508,9 @@ static int __fallback_sds_alloc(struct s_data *d, unsig= ned long *visited_nodes) return -ENOMEM; =20 d->fallback_nohz_sds[j] =3D sds; + + if (__sds_nohz_idle_alloc(sds, j)) + return -ENOMEM; } =20 return 0; @@ -502,8 +523,10 @@ static void __fallback_sds_free(struct s_data *d) if (!d->fallback_nohz_sds) return; =20 - for (j =3D 0; j < nr_node_ids; ++j) + for (j =3D 0; j < nr_node_ids; ++j) { + __sds_nohz_idle_free(d->fallback_nohz_sds[j]); kfree(d->fallback_nohz_sds[j]); + } =20 kfree(d->fallback_nohz_sds); d->fallback_nohz_sds =3D NULL; @@ -553,6 +576,13 @@ static void update_nohz_domain(int cpu) =20 #else /* !CONFIG_NO_HZ_COMMON */ =20 +static int __sds_nohz_idle_alloc(struct sched_domain_shared *sds, int node) +{ + return 0; +} + +static void __sds_nohz_idle_free(struct sched_domain_shared *sds) { } + static inline int __fallback_sds_alloc(struct s_data *d, unsigned long *vi= sited_nodes) { return 0; @@ -740,8 +770,10 @@ static void destroy_sched_domain(struct sched_domain *= sd) */ free_sched_groups(sd->groups, 1); =20 - if (sd->shared && atomic_dec_and_test(&sd->shared->ref)) + if (sd->shared && atomic_dec_and_test(&sd->shared->ref)) { + __sds_nohz_idle_free(sd->shared); kfree(sd->shared); + } kfree(sd); } =20 @@ -2599,6 +2631,9 @@ static int __sds_alloc(struct s_data *d, const struct= cpumask *cpu_map) =20 bitmap_set(visited_nodes, cpu_to_node(j), 1); *per_cpu_ptr(d->sds, j) =3D sds; + + if (__sds_nohz_idle_alloc(sds, cpu_to_node(j))) + return -ENOMEM; } =20 if (__fallback_sds_alloc(d, visited_nodes)) @@ -2614,8 +2649,13 @@ static void __sds_free(struct s_data *d, const struc= t cpumask *cpu_map) if (!d->sds) return; =20 - for_each_cpu(j, cpu_map) - kfree(*per_cpu_ptr(d->sds, j)); + for_each_cpu(j, cpu_map) { + struct sched_domain_shared *sds; + + sds =3D *per_cpu_ptr(d->sds, j); + __sds_nohz_idle_free(sds); + kfree(sds); + } =20 __fallback_sds_free(d); =20 --=20 2.43.0