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

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