On 2/1/22 14:53, David Woodhouse wrote:
Doing the INIT/SIPI/SIPI in parallel for all APs and *then* waiting for
them shaves about 80% off the AP bringup time on a 96-thread 2-socket
Skylake box (EC2 c5.metal) — from about 500ms to 100ms.
There are more wins to be had with further parallelisation, but this is
the simple part.
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 :)
I'm no longer seeing crashes launching high vCPU-count guests with this
series.
Thanks,
Tom
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
[dwoodhou@i7 linux-2.6]$ git diff --stat v5.17-rc2..share/parallel-5.17-part1
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 | 325 ++++++++++++++++++++++++----------
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, 442 insertions(+), 161 deletions(-)
