AuxXxilium/linux_dsm_epyc7002
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51204e0639
linux_dsm_epyc7002/arch/x86/kernel
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Len Brown 51204e0639 x86: do not use cpufreq_quick_get() for /proc/cpuinfo "cpu MHz" 
cpufreq_quick_get() allows cpufreq drivers to over-ride cpu_khz
that is otherwise reported in x86 /proc/cpuinfo "cpu MHz".

There are four problems with this scheme,
any of them is sufficient justification to delete it.

 1. Depending on which cpufreq driver is loaded, the behavior
    of this field is different.

 2. Distros complain that they have to explain to users
    why and how this field changes.  Distros have requested a constant.

 3. The two major providers of this information, acpi_cpufreq
    and intel_pstate, both "get it wrong" in different ways.

    acpi_cpufreq lies to the user by telling them that
    they are running at whatever frequency was last
    requested by software.

    intel_pstate lies to the user by telling them that
    they are running at the average frequency computed
    over an undefined measurement.  But an average computed
    over an undefined interval, is itself, undefined...

 4. On modern processors, user space utilities, such as
    turbostat(1), are more accurate and more precise, while
    supporing concurrent measurement over arbitrary intervals.

Users who have been consulting /proc/cpuinfo to
track changing CPU frequency will be dissapointed that
it no longer wiggles -- perhaps being unaware of the
limitations of the information they have been consuming.

Yes, they can change their scripts to look in sysfs
cpufreq/scaling_cur_frequency.  Here they will find the same
data of dubious quality here removed from /proc/cpuinfo.
The value in sysfs will be addressed in a subsequent patch
to address issues 1-3, above.

Issue 4 will remain -- users that really care about
accurate frequency information should not be using either
proc or sysfs kernel interfaces.
They should be using using turbostat(8), or a similar
purpose-built analysis tool.

Signed-off-by: Len Brown <len.brown@intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-06-24 01:45:47 +02:00
..
acpi Merge branch 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-05-01 23:54:56 -07:00
apic Merge branch 'x86-apic-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-05-01 21:41:07 -07:00
cpu x86: do not use cpufreq_quick_get() for /proc/cpuinfo "cpu MHz" 2017-06-24 01:45:47 +02:00
fpu KVM: x86: Fix load damaged SSEx MXCSR register 2017-05-15 16:08:56 +02:00
kprobes kprobes/x86: Fix to set RWX bits correctly before releasing trampoline 2017-05-26 22:37:00 -04:00
.gitignore
alternative.c x86/alternatives: Prevent uninitialized stack byte read in apply_alternatives() 2017-05-24 16:18:12 +02:00
amd_gart_64.c x86: use set_memory.h header 2017-05-08 17:15:13 -07:00
amd_nb.c x86/amd_nb: Add SMN and Indirect Data Fabric access for AMD Fam17h 2016-11-16 20:46:38 +01:00
apb_timer.c Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-12-25 14:30:04 -08:00
aperture_64.c x86/boot/e820: Prefix the E820_* type names with "E820_TYPE_" 2017-01-28 22:55:22 +01:00
apm_32.c x86: Remap GDT tables in the fixmap section 2017-03-16 09:06:35 +01:00
asm-offsets_32.c
asm-offsets_64.c x86/kvm: Provide optimized version of vcpu_is_preempted() for x86-64 2017-02-21 12:48:35 +01:00
asm-offsets.c efi: Get and store the secure boot status 2017-02-07 10:42:10 +01:00
audit_64.c
bootflag.c
check.c
cpuid.c Merge branch 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-12-12 19:25:04 -08:00
crash_dump_32.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
crash_dump_64.c
crash.c x86/boot/e820: Clean up the E820 table size define names 2017-01-28 22:55:23 +01:00
devicetree.c
doublefault.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/debug.h> 2017-03-02 08:42:34 +01:00
dumpstack_32.c x86/debug: Implement __WARN() using UD0 2017-03-27 10:20:28 +02:00
dumpstack_64.c x86/debug: Implement __WARN() using UD0 2017-03-27 10:20:28 +02:00
dumpstack.c x86/unwind: Ensure stack pointer is aligned 2017-04-18 10:30:23 +02:00
e820.c x86/boot/e820: Remove a redundant self assignment 2017-04-14 11:43:21 +02:00
early_printk.c x86/earlyprintk: Add support for earlyprintk via USB3 debug port 2017-03-21 12:30:16 +01:00
early-quirks.c main drm pull request for 4.12 kernel 2017-05-03 11:44:24 -07:00
ebda.c
espfix_64.c x86/espfix: Add support for 5-level paging 2017-04-04 08:22:34 +02:00
ftrace_32.S x86/ftrace: Fix ebp in ftrace_regs_caller that screws up unwinder 2017-04-21 09:48:16 +02:00
ftrace_64.S x86/ftrace: Use Makefile logic instead of #ifdef for compiling ftrace_*.o 2017-03-24 10:14:08 +01:00
ftrace.c x86/ftrace: Make sure that ftrace trampolines are not RWX 2017-05-26 22:37:02 -04:00
head32.c x86/boot/e820: Move asm/e820.h to asm/e820/api.h 2017-01-28 09:31:13 +01:00
head64.c Merge branch 'x86-boot-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-05-01 20:51:12 -07:00
head_32.S x86/boot/32: Convert the 32-bit pgtable setup code from assembly to C 2017-01-06 08:39:26 +01:00
head_64.S x86/boot/64: Rename start_cpu() 2017-03-07 13:57:25 +01:00
hpet.c x86/hpet: Prevent might sleep splat on resume 2017-03-02 09:33:47 +01:00
hw_breakpoint.c
i8237.c
i8253.c
i8259.c x86: i8259: export legacy_pic symbol 2017-04-14 12:08:51 +02:00
io_delay.c
ioport.c Second batch of KVM changes for 4.11 merge window 2017-03-04 11:36:19 -08:00
irq_32.c
irq_64.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task_stack.h> 2017-03-02 08:42:36 +01:00
irq_work.c x86/irq, trace: Add __irq_entry annotation to x86's platform IRQ handlers 2017-01-05 08:58:49 +01:00
irq.c x86/irq: Optimize free vector check in the CPU offline path 2017-04-20 15:25:09 +02:00
irqinit.c x86/irq: Remove a redundant #ifdef directive 2017-04-14 22:43:01 +02:00
itmt.c sched/x86: Remove unnecessary TBM3 check to update topology 2017-01-19 08:42:37 +01:00
jump_label.c locking/jump_labels: Update bug_at() boot message 2017-01-12 09:43:07 +01:00
kdebugfs.c x86/kdebugfs: Move boot params hierarchy under (debugfs)/x86/ 2017-03-01 09:57:02 +01:00
kexec-bzimage64.c x86/boot/e820: Clean up the E820 table size define names 2017-01-28 22:55:23 +01:00
kgdb.c
ksysfs.c
kvm.c kvm: async_pf: fix rcu_irq_enter() with irqs enabled 2017-06-06 14:43:16 +02:00
kvmclock.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/clock.h> 2017-03-02 08:42:27 +01:00
ldt.c Merge branch 'akpm' (patches from Andrew) 2016-12-12 20:50:02 -08:00
livepatch.c
machine_kexec_32.c x86: use set_memory.h header 2017-05-08 17:15:13 -07:00
machine_kexec_64.c Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-05-12 10:11:50 -07:00
Makefile x86/ftrace: Use Makefile logic instead of #ifdef for compiling ftrace_*.o 2017-03-24 10:14:08 +01:00
mmconf-fam10h_64.c
module.c mm, vmalloc: use __GFP_HIGHMEM implicitly 2017-05-08 17:15:13 -07:00
mpparse.c x86/boot/e820: Rename early_reserve_e820() to e820__memblock_alloc() and document it 2017-01-28 14:42:30 +01:00
msr.c x86/msr: Remove bogus cleanup from the error path 2016-12-25 10:47:41 +01:00
nmi_selftest.c
nmi.c * An EDAC driver for Cavium ThunderX RAS IP (Sergey Temerkhanov) 2017-05-01 11:36:00 -07:00
paravirt_patch_32.c x86/paravirt: Mark unused patch_default label 2016-12-22 17:43:35 +01:00
paravirt_patch_64.c x86/paravirt: Mark unused patch_default label 2016-12-22 17:43:35 +01:00
paravirt-spinlocks.c 4.11 is going to be a relatively large release for KVM, with a little over 2017-02-22 18:22:53 -08:00
paravirt.c x86/paravirt: Add 5-level support to the paravirt code 2017-04-04 08:22:34 +02:00
pci-calgary_64.c x86/pci-calgary: Use setup_timer() instead of open coding it. 2017-03-31 10:21:04 +02:00
pci-dma.c This is a tree wide change and has been kept separate for that reason. 2017-02-25 13:45:43 -08:00
pci-iommu_table.c
pci-nommu.c treewide: Constify most dma_map_ops structures 2017-01-24 12:23:35 -05:00
pci-swiotlb.c treewide: Constify most dma_map_ops structures 2017-01-24 12:23:35 -05:00
pcspeaker.c
perf_regs.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task_stack.h> 2017-03-02 08:42:36 +01:00
platform-quirks.c x86/init: Add i8042 state to the platform data 2016-12-19 11:34:15 +01:00
pmem.c
probe_roms.c x86/boot/e820: Move asm/e820.h to asm/e820/api.h 2017-01-28 09:31:13 +01:00
process_32.c x86/debug/32: Convert a smp_processor_id() call to raw to avoid DEBUG_PREEMPT warning 2017-05-29 08:22:49 +02:00
process_64.c x86/xen: add CONFIG_XEN_PV to Kconfig 2017-05-02 10:50:19 +02:00
process.c x86/arch_prctl: Add ARCH_[GET|SET]_CPUID 2017-03-20 16:10:34 +01:00
ptrace.c x86/arch_prctl/64: Rename do_arch_prctl() to do_arch_prctl_64() 2017-03-20 16:10:32 +01:00
pvclock.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/nmi.h> 2017-03-02 08:42:30 +01:00
quirks.c x86/quirks: Hide maybe-uninitialized warning 2016-10-25 11:45:13 +02:00
reboot_fixups_32.c
reboot.c x86/mce: Handle broadcasted MCE gracefully with kexec 2017-03-13 20:18:07 +01:00
relocate_kernel_32.S
relocate_kernel_64.S
resource.c x86/boot/e820: Harmonize the 'struct e820_table' fields 2017-01-28 09:33:16 +01:00
rtc.c timekeeping: Ignore the bogus sleep time if pm_trace is enabled 2016-11-29 18:02:58 +01:00
setup_percpu.c x86/boot/32: Fix UP boot on Quark and possibly other platforms 2017-05-09 08:14:24 +02:00
setup.c x86/timers: Move simple_udelay_calibration past init_hypervisor_platform 2017-05-26 13:04:09 +02:00
signal_compat.c x86/signals: Fix lower/upper bound reporting in compat siginfo 2017-04-05 10:16:43 +02:00
signal.c x86/debug: Fix the printk() debug output of signal_fault(), do_trap() and do_general_protection() 2017-04-11 09:11:13 +02:00
smp.c Merge branch 'x86-boot-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-05-01 20:51:12 -07:00
smpboot.c x86: Remap GDT tables in the fixmap section 2017-03-16 09:06:35 +01:00
stacktrace.c stacktrace/x86: add function for detecting reliable stack traces 2017-03-08 09:18:02 +01:00
step.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task_stack.h> 2017-03-02 08:42:36 +01:00
sys_x86_64.c mm: larger stack guard gap, between vmas 2017-06-19 21:50:20 +08:00
sysfb_efi.c
sysfb_simplefb.c x86/sysfb: Fix lfb_size calculation 2016-11-16 09:38:23 +01:00
sysfb.c
tboot.c IOMMU Updates for Linux v4.12 2017-05-09 15:15:47 -07:00
tce_64.c
time.c
tls.c x86/tls: Forcibly set the accessed bit in TLS segments 2017-03-19 12:14:35 +01:00
tls.h
topology.c
trace_clock.c
tracepoint.c tracing: Have the reg function allow to fail 2016-12-09 09:13:30 -05:00
traps.c x86/debug: Handle early WARN_ONs proper 2017-06-12 21:17:48 +02:00
tsc_msr.c x86/tsc: Set TSC_KNOWN_FREQ and TSC_RELIABLE flags on Intel Atom SoCs 2016-11-18 10:58:31 +01:00
tsc_sync.c x86/tsc: Make the TSC ADJUST sanitizing work for tsc_reliable 2017-02-10 09:47:17 +01:00
tsc.c sched/clock, x86/perf: Fix "perf test tsc" 2017-03-23 07:31:49 +01:00
unwind_frame.c x86/unwind: Add end-of-stack check for ftrace handlers 2017-05-24 09:05:16 +02:00
unwind_guess.c x86/unwind: Ensure stack pointer is aligned 2017-04-18 10:30:23 +02:00
uprobes.c
verify_cpu.S
vm86_32.c x86/vm86/32: Switch to flush_tlb_mm_range() in mark_screen_rdonly() 2017-04-26 10:02:06 +02:00
vmlinux.lds.S debug: Fix __bug_table[] in arch linker scripts 2017-04-03 10:22:40 +02:00
vsmp_64.c
x86_init.c x86/boot/e820: Rename default_machine_specific_memory_setup() to e820__memory_setup_default() 2017-01-28 14:42:26 +01:00