[PATCH 0/2] x86/smpboot: tidy sched-topology and drop useless SMT level

From: Li Chen
Date: Tue Jun 24 2025 - 04:10:03 EST


From: Li Chen <chenl311@xxxxxxxxxxxxxxx>

This two–patch series cleans up sched-domain topology handling and
eliminates hundreds of pointless attach/destroy cycles 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.

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(-)

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2.49.0