Dusting off this patch series from February, in which we reduce the time
taken for bringing up CPUs on a 96-way Skylake box from 500ms to about
34ms.
There is more parallelism to be had here, including a 1:many TSC sync
(or just *no* TSC sync, in the kexec case), and letting the APs all run
through their own states from CPUHP_BRINGUP_CPU to CPUHP_AP_ONLINE_IDLE
in parallel too. But I'll take a mere factor of 15 for the time being.
We can also have a careful look at the remaining time spent in the
initial INIT/SIPI phase and see what we can shave off it.
David Woodhouse (10):
x86/apic/x2apic: Fix parallel handling of cluster_mask
rcu: Kill rnp->ofl_seq and use only rcu_state.ofl_lock for exclusion
rcu: Add mutex for rcu boost kthread spawning and affinity setting
cpu/hotplug: Add dynamic parallel bringup states before CPUHP_BRINGUP_CPU
x86/smpboot: Reference count on smpboot_setup_warm_reset_vector()
x86/smpboot: Split up native_cpu_up into separate phases
cpu/hotplug: Move idle_thread_get() to <linux/smpboot.h>
x86/tsc: Avoid synchronizing TSCs with multiple CPUs in parallel
x86/smp: Bring up secondary CPUs in parallel
x86/kvm: Silence per-cpu pr_info noise about KVM clocks and steal time
Thomas Gleixner (1):
x86/boot: Support parallel startup of secondary CPUs
arch/x86/include/asm/realmode.h | 3 +++
arch/x86/include/asm/smp.h | 9 ++++++-
arch/x86/kernel/acpi/sleep.c | 1 +
arch/x86/kernel/apic/apic.c | 2 +-
arch/x86/kernel/apic/x2apic_cluster.c | 82 +++++++++++++++++++++++++++++++++++++-------------------------
arch/x86/kernel/head_64.S | 71 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
arch/x86/kernel/kvm.c | 6 ++---
arch/x86/kernel/kvmclock.c | 2 +-
arch/x86/kernel/smpboot.c | 243 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-------------------------------------------------
arch/x86/kernel/tsc_sync.c | 7 ++++++
arch/x86/realmode/init.c | 3 +++
arch/x86/realmode/rm/trampoline_64.S | 14 +++++++++++
include/linux/cpuhotplug.h | 2 ++
include/linux/smpboot.h | 7 ++++++
kernel/cpu.c | 27 +++++++++++++++++++--
kernel/rcu/tree.c | 65 ++++++++++++++++++++++++-------------------------
kernel/rcu/tree.h | 7 +++---
kernel/rcu/tree_plugin.h | 10 ++++++--
kernel/smpboot.c | 2 +-
kernel/smpboot.h | 2 --
20 files changed, 418 insertions(+), 147 deletions(-)
