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From: Li Chen <me@linux.beauty>
To: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86@kernel.org, "H . Peter Anvin" <hpa@zytor.com>,
	"Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	K Prateek Nayak <kprateek.nayak@amd.com>,
	Sohil Mehta <sohil.mehta@intel.com>,
	Brian Gerst <brgerst@gmail.com>,
	Patryk Wlazlyn <patryk.wlazlyn@linux.intel.com>,
	linux-kernel@vger.kernel.org
Subject: [PATCH v3 0/2] x86/smpboot: tidy sched-topology and drop useless SMT level
Date: Wed, 25 Jun 2025 11:45:48 +0800	[thread overview]
Message-ID: <20250625034552.42365-1-me@linux.beauty> (raw)

From: Li Chen <chenl311@chinatelecom.cn>

This two–patch series cleans up sched-domain topology handling and
eliminates hundreds of pointless attach/destroy cycles for large
machines when SMT is not available.

Patch 1 (from Thomas, unchanged) gets rid of the #ifdef maze in
build_sched_topology() by statically initialising the topology array.

Patch 2 (mine) is a follow-up that simply memmoves the array when
cpu_smt_num_threads <= 1, so the SMT level never gets created and
immediately torn down again.

Tested on Qemu.

changelog:
v2: fix wording issue as suggested by Thomas [1]
v3: remove pointless memset and adjust PKG index accordingly, as
    suggested by Thomas [2], and refine some other wording issues.

[1]: https://lore.kernel.org/all/87msa2r018.ffs@tglx/
[2]: https://lore.kernel.org/all/875xglntx1.ffs@tglx/

Li Chen (1):
  x86/smpboot: avoid SMT domain attach/destroy if SMT is not enabled

Thomas Gleixner (1):
  x86/smpboot: Decrapify build_sched_topology()

 arch/x86/kernel/smpboot.c | 59 +++++++++++++++++++++------------------
 1 file changed, 32 insertions(+), 27 deletions(-)

-- 
2.49.0


             reply	other threads:[~2025-06-25  3:46 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-06-25  3:45 Li Chen [this message]
2025-06-25  3:45 ` [PATCH v3 1/2] x86/smpboot: Decrapify build_sched_topology() Li Chen
2025-06-25  8:28   ` Peter Zijlstra
2025-06-30  0:21     ` Li Chen
2025-06-30 12:56       ` Thomas Gleixner
2025-06-25  3:45 ` [PATCH v3 2/2] x86/smpboot: avoid SMT domain attach/destroy if SMT is not enabled Li Chen
2025-06-25  5:45   ` K Prateek Nayak
2025-06-25  8:30     ` Peter Zijlstra
2025-06-30  0:39     ` Li Chen
2025-06-25  8:29   ` Peter Zijlstra
2025-06-30  0:29     ` Li Chen
2025-06-25  5:50 ` [PATCH v3 0/2] x86/smpboot: tidy sched-topology and drop useless SMT level K Prateek Nayak

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