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2207def700
linux_dsm_epyc7002/arch/x86/kernel
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Thomas Gleixner 2207def700 x86/apic: Ignore secondary threads if nosmt=force 
nosmt on the kernel command line merely prevents the onlining of the
secondary SMT siblings.

nosmt=force makes the APIC detection code ignore the secondary SMT siblings
completely, so they even do not show up as possible CPUs. That reduces the
amount of memory allocations for per cpu variables and saves other
resources from being allocated too large.

This is not fully equivalent to disabling SMT in the BIOS because the low
level SMT enabling in the BIOS can result in partitioning of resources
between the siblings, which is not undone by just ignoring them. Some CPUs
can use the full resources when their sibling is not onlined, but this is
depending on the CPU family and model and it's not well documented whether
this applies to all partitioned resources. That means depending on the
workload disabling SMT in the BIOS might result in better performance.

Linus analysis of the Intel manual:

  The intel optimization manual is not very clear on what the partitioning
  rules are.

  I find:

    "In general, the buffers for staging instructions between major pipe
     stages  are partitioned. These buffers include µop queues after the
     execution trace cache, the queues after the register rename stage, the
     reorder buffer which stages instructions for retirement, and the load
     and store buffers.

     In the case of load and store buffers, partitioning also provided an
     easier implementation to maintain memory ordering for each logical
     processor and detect memory ordering violations"

  but some of that partitioning may be relaxed if the HT thread is "not
  active":

    "In Intel microarchitecture code name Sandy Bridge, the micro-op queue
     is statically partitioned to provide 28 entries for each logical
     processor,  irrespective of software executing in single thread or
     multiple threads. If one logical processor is not active in Intel
     microarchitecture code name Ivy Bridge, then a single thread executing
     on that processor  core can use the 56 entries in the micro-op queue"

  but I do not know what "not active" means, and how dynamic it is. Some of
  that partitioning may be entirely static and depend on the early BIOS
  disabling of HT, and even if we park the cores, the resources will just be
  wasted.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
2018-06-21 14:21:00 +02:00
..
acpi x86/apic: Ignore secondary threads if nosmt=force 2018-06-21 14:21:00 +02:00
apic x86/apic: Ignore secondary threads if nosmt=force 2018-06-21 14:21:00 +02:00
cpu x86/cpu/AMD: Evaluate smp_num_siblings early 2018-06-21 14:21:00 +02:00
fpu Merge commit 'upstream-x86-entry' into WIP.x86/mm 2017-12-17 12:58:53 +01:00
kprobes kprobes/x86: Prohibit probing on exception masking instructions 2018-05-13 19:52:55 +02:00
.gitignore
alternative.c x86/paravirt: Remove 'noreplace-paravirt' cmdline option 2018-01-31 10:37:45 +01:00
amd_gart_64.c x86/dma/amd_gart: Use dma_direct_{alloc,free}() 2018-03-20 10:01:57 +01:00
amd_nb.c x86/amd_nb: Add support for Raven Ridge CPUs 2018-05-13 09:00:27 -07:00
apb_timer.c
aperture_64.c x86/gart: Exclude GART aperture from vmcore 2018-01-11 15:09:24 +01:00
apm_32.c Merge branch 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-06-04 19:17:47 -07:00
asm-offsets_32.c Kbuild: rename CC_STACKPROTECTOR[_STRONG] config variables 2018-06-14 12:21:18 +09:00
asm-offsets_64.c Kbuild: rename CC_STACKPROTECTOR[_STRONG] config variables 2018-06-14 12:21:18 +09:00
asm-offsets.c Kbuild: rename CC_STACKPROTECTOR[_STRONG] config variables 2018-06-14 12:21:18 +09:00
audit_64.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
bootflag.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
check.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
cpuid.c x86/cpuid: Allow cpuid_read() to schedule 2018-03-27 12:01:48 +02:00
crash_dump_32.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
crash_dump_64.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
crash.c kexec_file, x86: move re-factored code to generic side 2018-04-13 17:10:27 -07:00
devicetree.c Merge branch 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-04-02 16:15:32 -07:00
doublefault.c x86/entry: Fix assumptions that the HW TSS is at the beginning of cpu_tss 2017-12-17 13:59:55 +01:00
dumpstack_32.c x86/dumpstack: Unify show_regs() 2018-03-08 12:04:59 +01:00
dumpstack_64.c x86/dumpstack: Unify show_regs() 2018-03-08 12:04:59 +01:00
dumpstack.c x86/dumpstack: Explain the reasoning for the prologue and buffer size 2018-04-26 16:15:28 +02:00
e820.c x86: Remove pr_fmt duplicate logging prefixes 2018-05-13 21:25:18 +02:00
early_printk.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
early-quirks.c x86/early-quirks: Rename duplicate define of dev_err 2018-05-13 20:04:35 +02:00
ebda.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
eisa.c x86/eisa: Add missing include 2017-08-31 21:34:48 +02:00
espfix_64.c x86/espfix: Document use of _PAGE_GLOBAL 2018-04-09 18:27:33 +02:00
ftrace_32.S x86/retpoline/ftrace: Convert ftrace assembler indirect jumps 2018-01-12 00:14:30 +01:00
ftrace_64.S Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-01-28 12:19:23 -08:00
ftrace.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
head32.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
head64.c x86/mm: Mark __pgtable_l5_enabled __initdata 2018-05-19 11:56:58 +02:00
head_32.S Kbuild: rename CC_STACKPROTECTOR[_STRONG] config variables 2018-06-14 12:21:18 +09:00
head_64.S x86/mm: Comment _PAGE_GLOBAL mystery 2018-04-12 09:05:58 +02:00
hpet.c treewide: kzalloc() -> kcalloc() 2018-06-12 16:19:22 -07:00
hw_breakpoint.c
i8237.c x86/i8237: Register device based on FADT legacy boot flag 2018-04-27 16:44:29 +02:00
i8253.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
i8259.c Merge branch 'linus' into x86/apic, to resolve conflicts 2017-11-07 10:51:10 +01:00
idt.c x86/idt: Simplify the idt_setup_apic_and_irq_gates() 2018-06-06 13:38:01 +02:00
io_delay.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ioport.c x86/ioport: add ksys_ioperm() helper; remove in-kernel calls to sys_ioperm() 2018-04-02 20:16:12 +02:00
irq_32.c x86/retpoline/irq32: Convert assembler indirect jumps 2018-01-12 00:14:32 +01:00
irq_64.c x86/irq/64: Print the offending IP in the stack overflow warning 2017-12-17 13:59:53 +01:00
irq_work.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
irq.c Drivers: hv: vmbus: Implement Direct Mode for stimer0 2018-03-06 09:57:17 -08:00
irqinit.c x86/apic: Simplify init_bsp_APIC() usage 2018-02-13 17:30:38 +01:00
itmt.c x86/headers: Remove duplicate #includes 2017-12-12 11:32:24 +01:00
jailhouse.c x86: Convert x86_platform_ops to timespec64 2018-05-19 14:03:14 +02:00
jump_label.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
kdebugfs.c x86, mpparse, x86/acpi, x86/PCI, x86/dmi, SFI: Use memremap() for RAM mappings 2017-07-18 11:37:58 +02:00
kexec-bzimage64.c kexec_file: do not add extra alignment to efi memmap 2018-04-20 17:18:36 -07:00
kgdb.c
ksysfs.c treewide: kmalloc() -> kmalloc_array() 2018-06-12 16:19:22 -07:00
kvm.c kvm: rename KVM_HINTS_DEDICATED to KVM_HINTS_REALTIME 2018-05-17 19:12:13 +02:00
kvmclock.c x86: Convert x86_platform_ops to timespec64 2018-05-19 14:03:14 +02:00
ldt.c x86/ldt: Fix support_pte_mask filtering in map_ldt_struct() 2018-04-16 11:20:34 -07:00
livepatch.c
machine_kexec_32.c x86/kexec: Avoid double free_page() upon do_kexec_load() failure 2018-05-13 19:50:06 +02:00
machine_kexec_64.c x86/mm: Stop pretending pgtable_l5_enabled is a variable 2018-05-19 11:56:57 +02:00
Makefile Merge branch 'x86-dma-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-04-02 17:18:45 -07:00
mmconf-fam10h_64.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
module.c x86: Treat R_X86_64_PLT32 as R_X86_64_PC32 2018-02-22 09:01:10 -08:00
mpparse.c Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-02-14 17:02:15 -08:00
msr.c
nmi_selftest.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
nmi.c locking/atomics: COCCINELLE/treewide: Convert trivial ACCESS_ONCE() patterns to READ_ONCE()/WRITE_ONCE() 2017-10-25 11:01:08 +02:00
paravirt_patch_32.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
paravirt_patch_64.c x86/paravirt: Dont patch flush_tlb_single 2017-12-17 14:27:52 +01:00
paravirt-spinlocks.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
paravirt.c x86/mm: Rename flush_tlb_single() and flush_tlb_one() to __flush_tlb_one_[user|kernel]() 2018-02-15 01:15:52 +01:00
pci-calgary_64.c x86/dma: Remove dma_alloc_coherent_gfp_flags() 2018-03-20 10:01:58 +01:00
pci-dma.c x86/pci-dma: switch the VIA 32-bit DMA quirk to use the struct device flag 2018-05-28 12:48:25 +02:00
pci-iommu_table.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
pci-swiotlb.c x86/dma: Use generic swiotlb_ops 2018-03-20 10:01:57 +01:00
pcspeaker.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
perf_regs.c perf/x86: Store user space frame-pointer value on a sample 2018-05-25 08:11:12 +02:00
platform-quirks.c x86/i8237: Register device based on FADT legacy boot flag 2018-04-27 16:44:29 +02:00
pmem.c resource: Provide resource struct in resource walk callback 2017-11-07 15:35:57 +01:00
probe_roms.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
process_32.c x86/dumpstack: Add a show_ip() function 2018-04-26 16:15:27 +02:00
process_64.c x86/mm: Drop TS_COMPAT on 64-bit exec() syscall 2018-05-19 12:31:05 +02:00
process.c x86/speculation: Rework speculative_store_bypass_update() 2018-05-17 17:09:19 +02:00
ptrace.c signal: Ensure every siginfo we send has all bits initialized 2018-04-25 10:40:51 -05:00
pvclock.c x86: Convert x86_platform_ops to timespec64 2018-05-19 14:03:14 +02:00
quirks.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
reboot_fixups_32.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
reboot.c x86/apic: Fix restoring boot IRQ mode in reboot and kexec/kdump 2018-02-17 11:47:45 +01:00
relocate_kernel_32.S
relocate_kernel_64.S x86/kexec: Make kexec (mostly) work in 5-level paging mode 2018-01-31 08:39:40 +01:00
resource.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
rtc.c x86: Convert x86_platform_ops to timespec64 2018-05-19 14:03:14 +02:00
setup_percpu.c x86/cpu_entry_area: Sync cpu_entry_area to initial_page_table 2018-03-01 09:48:27 +01:00
setup.c x86/speculation/l1tf: Make sure the first page is always reserved 2018-06-20 19:10:00 +02:00
signal_compat.c signal: Add TRAP_UNK si_code for undiagnosted trap exceptions 2018-04-25 10:40:56 -05:00
signal.c x86: Add support for restartable sequences 2018-06-06 11:58:32 +02:00
smp.c x86/tracing: Disentangle pagefault and resched IPI tracing key 2017-08-29 11:42:29 +02:00
smpboot.c x86/topology: Provide topology_smt_supported() 2018-06-21 14:20:57 +02:00
stacktrace.c Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-01-03 16:41:07 -08:00
step.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
sys_x86_64.c compat: Move compat_timespec/ timeval to compat_time.h 2018-04-19 13:29:54 +02:00
sysfb_efi.c
sysfb_simplefb.c
sysfb.c
tboot.c x86/pti: Make unpoison of pgd for trusted boot work for real 2018-01-11 23:36:59 +01:00
tce_64.c
time.c x86/time: Unconditionally register legacy timer interrupt 2018-01-14 20:18:23 +01:00
tls.c x86/ldt: Make the LDT mapping RO 2017-12-23 21:13:01 +01:00
tls.h
topology.c
trace_clock.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
tracepoint.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
traps.c signal: Ensure every siginfo we send has all bits initialized 2018-04-25 10:40:51 -05:00
tsc_msr.c
tsc_sync.c Merge branch 'x86-timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-11-13 19:07:38 -08:00
tsc.c x86/tsc: Fix mark_tsc_unstable() 2018-05-02 16:10:40 +02:00
umip.c signal: Ensure every siginfo we send has all bits initialized 2018-04-25 10:40:51 -05:00
unwind_frame.c x86/unwind: Disable unwinder warnings on 32-bit 2017-10-10 12:49:49 +02:00
unwind_guess.c x86/unwind: Add the ORC unwinder 2017-07-26 13:18:20 +02:00
unwind_orc.c extable: Make init_kernel_text() global 2018-02-21 16:54:06 +01:00
uprobes.c Merge branch 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-06-04 19:17:47 -07:00
verify_cpu.S x86/boot: Annotate verify_cpu() as a callable function 2017-09-28 09:39:03 +02:00
vm86_32.c x86/vm86/32: Fix POPF emulation 2018-03-14 09:21:01 +01:00
vmlinux.lds.S x86/build: Remove no-op macro VMLINUX_SYMBOL() 2018-05-13 15:11:34 +02:00
vsmp_64.c x86/apic: Remove unused callbacks 2017-09-25 20:51:58 +02:00
x86_init.c xen, mm: allow deferred page initialization for xen pv domains 2018-04-11 10:28:38 -07:00