This patchseries is from the work done by David Woodhouse (v4: https://lore.kernel.org/all/20220201205328.123066-1-dwmw2@xxxxxxxxxxxxx/). The parallel CPU bringup is disabled for all AMD CPUs in this version: (see discussions: https://lore.kernel.org/all/bc3f2b1332c4bb77558df8aa36493a55542fe5b9.camel@xxxxxxxxxxxxx/ and https://lore.kernel.org/all/3b6ac86fdc800cac5806433daf14a9095be101e9.camel@xxxxxxxxxxxxx/). Doing INIT/SIPI/SIPI in parallel brings down the time for smpboot from ~700ms to 100ms (85% improvement) on a server with 128 CPUs split across 2 NUMA nodes. Adding another cpuhp state for do_wait_cpu_initialized to make sure cpu_init is reached in parallel as proposed by David in v1 will bring it down further to ~30ms. Making this change would be dependent on this patchseries, so they could be explored if this gets merged. Changes across versions: v2: Cut it back to just INIT/SIPI/SIPI in parallel for now, nothing more v3: Clean up x2apic patch, add MTRR optimisation, lock topology update in preparation for more parallelisation. v4: Fixes to the real mode parallelisation patch spotted by SeanC, to avoid scribbling on initial_gs in common_cpu_up(), and to allow all 24 bits of the physical X2APIC ID to be used. That patch still needs a Signed-off-by from its original author, who once claimed not to remember writing it at all. But now we've fixed it, hopefully he'll admit it now :) v5: rebase to v6.1 and remeasure performance, disable parallel bringup for AMD CPUs. David Woodhouse (8): x86/apic/x2apic: Fix parallel handling of cluster_mask cpu/hotplug: Move idle_thread_get() to <linux/smpboot.h> 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 and document them x86/smpboot: Send INIT/SIPI/SIPI to secondary CPUs in parallel x86/mtrr: Avoid repeated save of MTRRs on boot-time CPU bringup x86/smpboot: Serialize topology updates for secondary bringup Thomas Gleixner (1): x86/smpboot: Support parallel startup of secondary CPUs arch/x86/include/asm/realmode.h | 3 + arch/x86/include/asm/smp.h | 13 +- arch/x86/include/asm/topology.h | 2 - arch/x86/kernel/acpi/sleep.c | 1 + arch/x86/kernel/apic/apic.c | 2 +- arch/x86/kernel/apic/x2apic_cluster.c | 108 +++++---- arch/x86/kernel/cpu/common.c | 6 +- arch/x86/kernel/cpu/mtrr/mtrr.c | 9 + arch/x86/kernel/head_64.S | 73 ++++++ arch/x86/kernel/smpboot.c | 324 ++++++++++++++++++-------- arch/x86/realmode/init.c | 3 + arch/x86/realmode/rm/trampoline_64.S | 14 ++ arch/x86/xen/smp_pv.c | 4 +- include/linux/cpuhotplug.h | 2 + include/linux/smpboot.h | 7 + kernel/cpu.c | 27 ++- kernel/smpboot.c | 2 +- kernel/smpboot.h | 2 - 18 files changed, 443 insertions(+), 159 deletions(-) -- 2.25.1
