linux/arch/x86/kernel
Giovanni Gherdovich 298c6f99bf x86, sched: Add support for frequency invariance on ATOM
The scheduler needs the ratio freq_curr/freq_max for frequency-invariant
accounting. On all ATOM CPUs prior to Goldmont, set freq_max to the 1-core
turbo ratio.

We intended to perform tests validating that this patch doesn't regress in
terms of energy efficiency, given that this is the primary concern on Atom
processors. Alas, we found out that turbostat doesn't support reading RAPL
interfaces on our test machine (Airmont), and we don't have external equipment
to measure power consumption; all we have is the performance results of the
benchmarks we ran.

Test machine:

Platform    : Dell Wyse 3040 Thin Client[1]
CPU Model   : Intel Atom x5-Z8350 (aka Cherry Trail, aka Airmont)
Fam/Mod/Ste : 6:76:4
Topology    : 1 socket, 4 cores / 4 threads
Memory      : 2G
Storage     : onboard flash, XFS filesystem

[1] https://www.dell.com/en-us/work/shop/wyse-endpoints-and-software/wyse-3040-thin-client/spd/wyse-3040-thin-client

Base frequency and available turbo levels (MHz):

    Min Operating Freq   266 |***
    Low Freq Mode        800 |********
    Base Freq           2400 |************************
    4 Cores             2800 |****************************
    3 Cores             2800 |****************************
    2 Cores             3200 |********************************
    1 Core              3200 |********************************

Tested kernels:

Baseline      : v5.4-rc1,              intel_pstate passive,  schedutil
Comparison #1 : v5.4-rc1,              intel_pstate active ,  powersave
Comparison #2 : v5.4-rc1, this patch,  intel_pstate passive,  schedutil

tbench, hackbench and kernbench performed the same under all three kernels;
dbench ran faster with intel_pstate/powersave and the git unit tests were a
lot faster with intel_pstate/powersave and invariant schedutil wrt the
baseline. Not that any of this is terrbily interesting anyway, one doesn't buy
an Atom system to go fast. Power consumption regressions aren't expected but
we lack the equipment to make that measurement. Turbostat seems to think that
reading RAPL on this machine isn't a good idea and we're trusting that
decision.

comparison ratio of performance with baseline; 1.00 means neutral,
lower is better:

                      I_PSTATE      FREQ-INV
    ----------------------------------------
    dbench                0.90             ~
    kernbench             0.98          0.97
    gitsource             0.63          0.43

Signed-off-by: Giovanni Gherdovich <ggherdovich@suse.cz>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lkml.kernel.org/r/20200122151617.531-6-ggherdovich@suse.cz
2020-01-28 21:37:05 +01:00
..
acpi x86/asm/32: Add ENDs to some functions and relabel with SYM_CODE_* 2019-10-18 11:58:33 +02:00
apic Merge branch 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-11-26 09:52:37 -08:00
cpu x86/mce: Fix possibly incorrect severity calculation on AMD 2019-12-17 09:39:53 +01:00
fpu treewide: Use sizeof_field() macro 2019-12-09 10:36:44 -08:00
kprobes Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-11-26 15:04:47 -08:00
.gitignore
Makefile x86/doublefault/32: Rename doublefault.c to doublefault_32.c 2019-11-26 21:53:34 +01:00
alternative.c x86/alternatives: Teach text_poke_bp() to emulate instructions 2019-11-15 14:07:01 -08:00
amd_gart_64.c dma-mapping updates for 5.5-rc1 2019-11-28 11:16:43 -08:00
amd_nb.c x86/amd_nb: Add PCI device IDs for family 17h, model 70h 2019-09-03 12:47:17 -07:00
apb_timer.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 441 2019-06-05 17:37:17 +02:00
aperture_64.c x86/gart: Exclude GART aperture from kcore 2019-03-23 12:11:49 +01:00
apm_32.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 118 2019-05-24 17:39:02 +02:00
asm-offsets.c x86/paravirt: Make read_cr2() CALLEE_SAVE 2019-07-17 23:17:37 +02:00
asm-offsets_32.c x86/entry/32: Load task stack from x86_tss.sp1 in SYSENTER handler 2018-07-20 01:11:36 +02:00
asm-offsets_64.c Merge branch 'x86-apic-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-09-17 12:04:39 -07:00
audit_64.c
bootflag.c
check.c x86/headers: Fix -Wmissing-prototypes warning 2018-11-23 07:59:59 +01:00
cpuid.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 142 2019-05-30 11:25:17 -07:00
crash.c x86/crash: Align function arguments on opening braces 2019-11-14 18:24:55 +01:00
crash_dump_32.c
crash_dump_64.c fs/core/vmcore: Move sev_active() reference to x86 arch code 2019-08-09 22:52:10 +10:00
devicetree.c x86/headers: Fix -Wmissing-prototypes warning 2018-11-23 07:59:59 +01:00
doublefault_32.c x86/doublefault/32: Rewrite the x86_32 #DF handler and unify with 64-bit 2019-11-26 22:00:04 +01:00
dumpstack.c x86/dumpstack: Indicate PREEMPT_RT in dumps 2019-07-31 19:03:36 +02:00
dumpstack_32.c x86/doublefault/32: Move #DF stack and TSS to cpu_entry_area 2019-11-26 21:53:34 +01:00
dumpstack_64.c x86/dumpstack/64: Don't evaluate exception stacks before setup 2019-11-05 00:51:35 +01:00
e820.c ACPI updates for 5.5-rc1 2019-11-26 19:25:25 -08:00
early-quirks.c x86/intel: Disable HPET on Intel Ice Lake platforms 2019-11-29 12:17:58 +01:00
early_printk.c efi/x86: Convert x86 EFI earlyprintk into generic earlycon implementation 2019-02-04 08:27:30 +01:00
ebda.c
eisa.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 243 2019-06-19 17:09:07 +02:00
espfix_64.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 288 2019-06-05 17:36:37 +02:00
ftrace.c ftrace: Fix function_graph tracer interaction with BPF trampoline 2019-12-10 13:53:59 -05:00
ftrace_32.S x86/ftrace: Get rid of function_hook 2019-10-25 10:52:22 +02:00
ftrace_64.S New tracing features: 2019-11-27 11:42:01 -08:00
head32.c x86/boot: Mostly revert commit ae7e1238e6 ("Add ACPI RSDP address to setup_header") 2018-11-20 09:43:10 +01:00
head64.c x86/boot/64: Make level2_kernel_pgt pages invalid outside kernel area 2019-10-11 18:38:15 +02:00
head_32.S Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-11-26 10:42:40 -08:00
head_64.S x86/asm/64: Change all ENTRY+END to SYM_CODE_* 2019-10-18 11:58:26 +02:00
hpet.c x86/hpet: Undo the early counter is counting check 2019-07-25 12:21:32 +02:00
hw_breakpoint.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156 2019-05-30 11:26:35 -07:00
i8237.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
i8253.c x86/timer: Skip PIT initialization on modern chipsets 2019-06-29 11:35:35 +02:00
i8259.c x86: Don't include linux/irq.h from asm/hardirq.h 2018-08-05 09:53:13 +02:00
idt.c Merge branch 'x86-apic-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-07-08 11:22:57 -07:00
ima_arch.c Merge branch 'next-lockdown' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2019-09-28 08:14:15 -07:00
io_delay.c x86/io_delay: Define IO_DELAY macros in C instead of Kconfig 2019-05-24 08:46:06 +02:00
ioport.c x86/ioperm: Extend IOPL config to control ioperm() as well 2019-11-16 11:24:06 +01:00
irq.c x86/irq: Check for VECTOR_UNUSED directly 2019-08-19 23:19:07 +02:00
irq_32.c x86/irq: Move IS_ERR_OR_NULL() check into common do_IRQ() code 2019-08-19 23:19:06 +02:00
irq_64.c x86/irq: Move IS_ERR_OR_NULL() check into common do_IRQ() code 2019-08-19 23:19:06 +02:00
irq_work.c
irqflags.S x86/asm: Change all ENTRY+ENDPROC to SYM_FUNC_* 2019-10-18 11:58:33 +02:00
irqinit.c x86/irq/32: Handle irq stack allocation failure proper 2019-04-17 15:31:42 +02:00
itmt.c proc/sysctl: add shared variables for range check 2019-07-18 17:08:07 -07:00
jailhouse.c x86/jailhouse: Only enable platform UARTs if available 2019-10-10 15:43:59 +02:00
jump_label.c x86/alternatives: Teach text_poke_bp() to emulate instructions 2019-11-15 14:07:01 -08:00
kdebugfs.c x86/boot: Introduce setup_indirect 2019-11-12 16:21:15 +01:00
kexec-bzimage64.c Merge branch 'next-lockdown' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2019-09-28 08:14:15 -07:00
kgdb.c x86/apic: Provide and use helper for send_IPI_allbutself() 2019-07-25 16:12:00 +02:00
ksysfs.c x86/boot: Introduce setup_indirect 2019-11-12 16:21:15 +01:00
kvm.c x86/kvm: Fix -Wmissing-prototypes warnings 2019-10-25 14:01:14 +02:00
kvmclock.c x86: kvmguest: use TSC clocksource if invariant TSC is exposed 2019-02-20 22:48:52 +01:00
ldt.c x86: Convert some slow-path static_cpu_has() callers to boot_cpu_has() 2019-04-08 12:13:34 +02:00
livepatch.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 13 2019-05-21 11:28:45 +02:00
machine_kexec_32.c x86/mm: Remove set_pages_x() and set_pages_nx() 2019-09-03 09:26:37 +02:00
machine_kexec_64.c x86/kdump: Remove the backup region handling 2019-11-14 18:24:43 +01:00
mmconf-fam10h_64.c
module.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156 2019-05-30 11:26:35 -07:00
mpparse.c x86/boot: Fix memory leak in default_get_smp_config() 2019-07-16 23:13:48 +02:00
msr.c x86/msr: Restrict MSR access when the kernel is locked down 2019-08-19 21:54:16 -07:00
nmi.c x86/hotplug: Silence APIC and NMI when CPU is dead 2019-07-25 16:11:59 +02:00
nmi_selftest.c
paravirt-spinlocks.c x86/paravirt: Use a single ops structure 2018-09-03 16:50:35 +02:00
paravirt.c x86/iopl: Remove legacy IOPL option 2019-11-16 11:24:05 +01:00
paravirt_patch.c x86/paravirt: Standardize 'insn_buff' variable names 2019-04-29 16:05:49 +02:00
pci-dma.c dma-mapping updates for 5.5-rc1 2019-11-28 11:16:43 -08:00
pci-iommu_table.c x86/iommu: Use NULL instead of 0 2018-08-02 14:33:19 +02:00
pci-swiotlb.c dma-mapping: fix filename references 2019-09-03 08:36:30 +02:00
pcspeaker.c x86/platform/pcspeaker: Use PTR_ERR_OR_ZERO() to fix ptr_ret.cocci warning 2018-07-24 09:46:42 +02:00
perf_regs.c perf/x86/regs: Check reserved bits 2019-06-24 19:19:24 +02:00
platform-quirks.c
pmem.c
probe_roms.c
process.c x86/ioperm: Save an indentation level in tss_update_io_bitmap() 2019-11-30 18:06:56 +01:00
process.h x86: Use the correct SPDX License Identifier in headers 2019-10-01 20:31:35 +02:00
process_32.c x86/iopl: Remove legacy IOPL option 2019-11-16 11:24:05 +01:00
process_64.c x86/iopl: Remove legacy IOPL option 2019-11-16 11:24:05 +01:00
ptrace.c x86/ptrace: Document FSBASE and GSBASE ABI oddities 2019-11-26 22:00:12 +01:00
pvclock.c x86/vdso: Switch to generic vDSO implementation 2019-06-22 21:21:10 +02:00
quirks.c x86/PCI: Remove superfluous returns from void functions 2019-08-20 09:54:36 +02:00
reboot.c x86/apic: Provide and use helper for send_IPI_allbutself() 2019-07-25 16:12:00 +02:00
reboot_fixups_32.c
relocate_kernel_32.S x86/asm: Annotate relocate_kernel_{32,64}.c 2019-10-18 09:53:19 +02:00
relocate_kernel_64.S x86/asm: Annotate relocate_kernel_{32,64}.c 2019-10-18 09:53:19 +02:00
resource.c
rtc.c
setup.c ACPI updates for 5.5-rc1 2019-11-26 19:25:25 -08:00
setup_percpu.c x86: Use pr_warn instead of pr_warning 2019-10-18 15:00:18 +02:00
signal.c x86: use static_cpu_has in uaccess region to avoid instrumentation 2019-07-12 11:05:42 -07:00
signal_compat.c
smp.c x86/smp: Move smp_function_call implementations into IPI code 2019-07-25 16:12:01 +02:00
smpboot.c x86, sched: Add support for frequency invariance on ATOM 2020-01-28 21:37:05 +01:00
stacktrace.c x86/stacktrace: Prevent access_ok() warnings in arch_stack_walk_user() 2019-07-22 10:42:36 +02:00
step.c
sys_x86_64.c x86/compat: Adjust in_compat_syscall() to generic code under !COMPAT 2018-11-01 12:59:25 +01:00
sysfb.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
sysfb_efi.c x86/sysfb_efi: Add quirks for some devices with swapped width and height 2019-07-22 10:47:11 +02:00
sysfb_simplefb.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
tboot.c x86: Use pr_warn instead of pr_warning 2019-10-18 15:00:18 +02:00
time.c Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-07-08 16:59:34 -07:00
tls.c x86/tls: Fix possible spectre-v1 in do_get_thread_area() 2019-06-27 23:48:04 +02:00
tls.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 193 2019-05-30 11:29:21 -07:00
topology.c x86/topology: Make DEBUG_HOTPLUG_CPU0 pr_info() more descriptive 2019-04-19 19:42:57 +02:00
trace_clock.c
tracepoint.c x86/kernel: Fix more -Wmissing-prototypes warnings 2018-12-08 12:24:35 +01:00
traps.c x86/traps: die() instead of panicking on a double fault 2019-11-26 22:00:12 +01:00
tsc.c x86/tsc: Respect tsc command line paraemeter for clocksource_tsc_early 2019-11-05 01:24:56 +01:00
tsc_msr.c x86/cpu: Update init data for new Airmont CPU model 2019-09-06 07:30:40 +02:00
tsc_sync.c x86: Use pr_warn instead of pr_warning 2019-10-18 15:00:18 +02:00
umip.c Merge branches 'x86-cpu-for-linus' and 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-11-26 08:58:08 -08:00
unwind_frame.c x86/stackframe/32: Provide consistent pt_regs 2019-06-25 10:23:47 +02:00
unwind_guess.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
unwind_orc.c Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-07-08 16:59:34 -07:00
uprobes.c x86/apic, x86/uprobes: Correct parameter names in kernel-doc comments 2019-10-27 09:00:28 +01:00
verify_cpu.S x86/asm: Annotate local pseudo-functions 2019-10-18 10:04:04 +02:00
vm86_32.c signal: Remove task parameter from force_sig 2019-05-27 09:36:28 -05:00
vmlinux.lds.S x86/vmlinux: Use INT3 instead of NOP for linker fill bytes 2019-11-04 19:10:08 +01:00
vsmp_64.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 346 2019-06-05 17:37:08 +02:00
x86_init.c x86/init: Allow DT configured systems to disable RTC at boot time 2019-11-12 15:46:53 +01:00