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From: Christian Loehle <christian.loehle@arm.com>
To: "Rafael J. Wysocki" <rafael@kernel.org>,
	linux-pm <linux-pm@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Subject: [PATCH] Revert "intel_idle: Rescan "dead" SMT siblings during, initialization"
Date: Thu, 28 Aug 2025 15:25:58 +0100	[thread overview]
Message-ID: <724616a2-6374-4ba3-8ce3-ea9c45e2ae3b@arm.com> (raw)

This reverts commit a430c11f401589a0f4f57fd398271a5d85142c7a.

Calling arch_cpu_rescan_dead_smt_siblings() in intel_idle_init with
boot parameter nosmt and maxcpus active hotplugged boot-offline CPUs
in (and leave them online) which weren't supposed to be online.

With the revert and nosmt and maxcpus=12 on a raptor lake:
cpu	online	capacity
cpu0	1	1009
cpu1	0	-
cpu2	1	1009
cpu3	0	-
cpu4	1	1009
cpu5	0	-
cpu6	1	1009
cpu7	0	-
cpu8	1	1024
cpu9	0	-
cpu10	1	1024
cpu11	0	-
cpu12	1	1009
cpu13	0	-
cpu14	1	1009
cpu15	0	-
cpu16	1	623
cpu17	1	623
cpu18	1	623
cpu19	1	623
cpu20	0	-
cpu21	0	-
cpu22	0	-
cpu23	0	-

Previously:
cpu	online	capacity
cpu0	1	1009
cpu1	0	-
cpu2	1	1009
cpu3	0	-
cpu4	1	1009
cpu5	0	-
cpu6	1	1009
cpu7	0	-
cpu8	1	1024
cpu9	0	-
cpu10	1	1024
cpu11	0	-
cpu12	1	1009
cpu13	0	-
cpu14	1	1009
cpu15	0	-
cpu16	1	623
cpu17	1	623
cpu18	1	623
cpu19	1	623
cpu20	1	623
cpu21	1	623
cpu22	1	623
cpu23	1	623

Signed-off-by: Christian Loehle <christian.loehle@arm.com>
---
Rafael, I don't immediately see how to fix this properly so I won't
try to, feel free to treat this as a bug report.


 drivers/idle/intel_idle.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
index 91a7b7e7c0c8..a9c58395a425 100644
--- a/drivers/idle/intel_idle.c
+++ b/drivers/idle/intel_idle.c
@@ -2507,8 +2507,6 @@ static int __init intel_idle_init(void)
 	pr_debug("Local APIC timer is reliable in %s\n",
 		 boot_cpu_has(X86_FEATURE_ARAT) ? "all C-states" : "C1");
 
-	arch_cpu_rescan_dead_smt_siblings();
-
 	return 0;
 
 hp_setup_fail:
-- 
2.34.1

             reply	other threads:[~2025-08-28 14:26 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-08-28 14:25 Christian Loehle [this message]
2025-08-28 14:44 ` Rafael J. Wysocki
2025-08-28 16:13   ` Rafael J. Wysocki
2025-08-28 19:06     ` Rafael J. Wysocki
2025-08-28 21:44       ` Christian Loehle
2025-08-29 17:49         ` Rafael J. Wysocki

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