[PATCH v6 00/11] Parallel CPU bringup for x86_64

From: Usama Arif <usama.arif@bytedance.com>
To: dwmw2@infradead.org, tglx@linutronix.de, arjan@linux.intel.com
Cc: mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com,
	hpa@zytor.com, x86@kernel.org, pbonzini@redhat.com,
	paulmck@kernel.org, linux-kernel@vger.kernel.org,
	kvm@vger.kernel.org, rcu@vger.kernel.org, mimoja@mimoja.de,
	hewenliang4@huawei.com, thomas.lendacky@amd.com,
	seanjc@google.com, pmenzel@molgen.mpg.de,
	fam.zheng@bytedance.com, punit.agrawal@bytedance.com,
	simon.evans@bytedance.com, liangma@liangbit.com,
	Usama Arif <usama.arif@bytedance.com>
Subject: [PATCH v6 00/11] Parallel CPU bringup for x86_64
Date: Thu,  2 Feb 2023 21:56:14 +0000	[thread overview]
Message-ID: <20230202215625.3248306-1-usama.arif@bytedance.com> (raw)

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.
The parallel CPU bringup is disabled for all AMD CPUs in this version: 
(see discussions: https://lore.kernel.org/all/bc3f2b1332c4bb77558df8aa36493a55542fe5b9.camel@infradead.org/ and
https://lore.kernel.org/all/3b6ac86fdc800cac5806433daf14a9095be101e9.camel@infradead.org/).

The last patch reuses the timer calibration from CPU 0 for secondary CPUs
which brings down the time for parallel smpboot from 100ms to 30ms. It is
missing a sign-off from the author, which hopefully Arjan will add.

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.
v6: rebase to v6.2-rc6, disabled parallel boot on amd as a cpu bug and
    reused timer calibration for secondary CPUs.

Arjan van de Ven (1):
  x86/smpboot: reuse timer calibration

David Woodhouse (9):
  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: Disable parallel boot for AMD CPUs
  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/cpufeatures.h    |   1 +
 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/amd.c             |  11 +
 arch/x86/kernel/cpu/common.c          |   6 +-
 arch/x86/kernel/cpu/mtrr/mtrr.c       |   9 +
 arch/x86/kernel/head_64.S             |  75 ++++++
 arch/x86/kernel/smpboot.c             | 333 ++++++++++++++++++--------
 arch/x86/kernel/tsc.c                 |   3 +
 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 -
 21 files changed, 469 insertions(+), 159 deletions(-)

-- 
2.25.1