]> git.ipfire.org Git - thirdparty/linux.git/commit
Reapply "x86/smp: Eliminate mwait_play_dead_cpuid_hint()"
authorRafael J. Wysocki <rafael.j.wysocki@intel.com>
Thu, 5 Jun 2025 15:09:35 +0000 (17:09 +0200)
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>
Sat, 7 Jun 2025 12:23:22 +0000 (14:23 +0200)
commita18d098f2aab82abde1d59c56aef9beca01c892b
treeee33c97b73f59f9ac4ab8dc45bfce702a1001e39
parentf694481b1d3177144fcac4242eb750cfcb9f7bd5
Reapply "x86/smp: Eliminate mwait_play_dead_cpuid_hint()"

Revert commit 70523f335734 ("Revert "x86/smp: Eliminate
mwait_play_dead_cpuid_hint()"") to reapply the changes from commit
96040f7273e2 ("x86/smp: Eliminate mwait_play_dead_cpuid_hint()")
reverted by it.

Previously, these changes caused idle power to rise on systems booting
with "nosmt" in the kernel command line because they effectively caused
"dead" SMT siblings to remain in idle state C1 after executing the HLT
instruction, which prevented the processor from reaching package idle
states deeper than PC2 going forward.

Now, the "dead" SMT siblings are rescanned after initializing a proper
cpuidle driver for the processor (either intel_idle or ACPI idle), at
which point they are able to enter a sufficiently deep idle state
in native_play_dead() via cpuidle, so the code changes in question can
be reapplied.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Tested-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Link: https://patch.msgid.link/7813065.EvYhyI6sBW@rjwysocki.net
arch/x86/kernel/smpboot.c