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linux-next/arch/x86/kernel
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Srivatsa S. Bhat 19209bbb86 x86/sched: Make mwait_usable() heed to "idle=" kernel parameters properly 
The checks that exist in mwait_usable() for "idle=" kernel
parameters are insufficient. As a result, mwait_usable() can
return 1 even if "idle=nomwait" or "idle=poll" or "idle=halt"
parameters are passed.

Of these cases, incorrect handling of idle=nomwait is a
universal problem since mwait can get used for usual CPU idling.
However the rest of the cases are problematic only during CPU
Hotplug (offline) because, in the CPU offline path, the function
mwait_play_dead() is called, which might result in mwait being
used in the offline CPUs, if mwait_usable() happens to return 1.

Fix these issues by checking for the boot time "idle=" kernel
parameter properly in mwait_usable().

The first issue (usual cpu idling) is demonstrated below:

Before applying the patch (dmesg snippet):

 [    0.000000] Command line: [...] idle=nomwait
 [    0.000000] Kernel command line: [...] idle=nomwait
 [    0.000000]  RCU dyntick-idle grace-period acceleration is enabled.
 [    0.140606] using mwait in idle threads.  <======= mwait being used
 [    4.303986] cpuidle: using governor ladder
 [    4.308232] cpuidle: using governor menu

After applying the patch:

 [    0.000000] Command line: [...] idle=nomwait
 [    0.000000] Kernel command line: [...] idle=nomwait
 [    0.000000]  RCU dyntick-idle grace-period acceleration is enabled.
 [    4.264100] cpuidle: using governor ladder
 [    4.268342] cpuidle: using governor menu

Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Acked-by: Deepthi Dharwar <deepthi@linux.vnet.ibm.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: venki@google.com
Cc: suresh.b.siddha@intel.com
Cc: Borislav Petkov <bp@amd64.org>
Cc: lenb@kernel.org
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Link: http://lkml.kernel.org/r/4F9E37B8.30001@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-05-07 16:27:20 +02:00
..
acpi x86, acpi: Call acpi_enter_sleep_state via an asmlinkage C function from assembler 2012-04-23 13:29:18 -07:00
apic x86/apic: Use x2apic physical mode based on FADT setting 2012-04-25 12:47:08 +02:00
cpu x86/amd: Re-enable CPU topology extensions in case BIOS has disabled it 2012-04-27 16:43:09 +02:00
.gitignore
alternative.c x86: Call stop_machine_text_poke() on all CPUs 2011-11-14 13:05:15 +01:00
amd_gart_64.c X86 & IA64: adapt for dma_map_ops changes 2012-03-28 16:36:31 +02:00
amd_nb.c Merge branch 'linux-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci 2012-01-11 18:50:26 -08:00
apb_timer.c Merge branch 'timers-clocksource-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-07-23 10:34:47 -07:00
aperture_64.c memblock, x86: Replace memblock_x86_reserve/free_range() with generic ones 2011-07-14 11:47:53 -07:00
apm_32.c Disintegrate asm/system.h for X86 2012-03-28 18:11:12 +01:00
asm-offsets_32.c x86: Generate system call tables and unistd_*.h from tables 2011-11-17 13:35:37 -08:00
asm-offsets_64.c x32: If configured, add x32 system calls to system call tables 2012-02-20 12:52:06 -08:00
asm-offsets.c x86, efi: EFI boot stub support 2011-12-12 14:26:10 -08:00
audit_64.c
bootflag.c
check.c memblock, x86: Replace memblock_x86_reserve/free_range() with generic ones 2011-07-14 11:47:53 -07:00
cpuid.c Disintegrate asm/system.h for X86 2012-03-28 18:11:12 +01:00
crash_dump_32.c x86: remove the second argument of k[un]map_atomic() 2012-03-20 21:48:15 +08:00
crash_dump_64.c crash_dump: export is_kdump_kernel to modules, consolidate elfcorehdr_addr, setup_elfcorehdr and saved_max_pfn 2011-03-23 19:47:19 -07:00
crash.c x86, nmi: Wire up NMI handlers to new routines 2011-10-10 06:56:57 +02:00
devicetree.c irq_domain/x86: Convert x86 (embedded) to use common irq_domain 2012-02-23 14:37:47 -07:00
doublefault_32.c
dumpstack_32.c x86/32: Print control and debug registers for kerenel context 2012-03-08 10:57:35 +01:00
dumpstack_64.c Merge branches 'core-urgent-for-linus', 'perf-urgent-for-linus', 'sched-urgent-for-linus' and 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-02-02 11:11:13 -08:00
dumpstack.c Merge branch 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-03-29 18:21:35 -07:00
e820.c Merge branch 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux 2012-01-18 15:51:48 -08:00
early_printk.c Merge branch 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-01-11 19:13:40 -08:00
early-quirks.c x86, quirk: Fix SB600 revision check 2011-03-16 14:03:32 +01:00
entry_32.S x86-32: Fix endless loop when processing signals for kernel tasks 2012-03-22 13:50:25 -07:00
entry_64.S Merge branch 'x86-x32-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-03-29 18:12:23 -07:00
ftrace.c x86/ftrace: Fix compiler warning in ftrace.c 2011-05-25 19:56:26 -04:00
head32.c memblock: Kill memblock_init() 2011-12-08 10:22:07 -08:00
head64.c memblock: Kill memblock_init() 2011-12-08 10:22:07 -08:00
head_32.S Merge branch 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-03-15 20:01:36 -07:00
head_64.S x86: Keep current stack in NMI breakpoints 2011-12-21 15:38:55 -05:00
head.c memblock, x86: Replace memblock_x86_reserve/free_range() with generic ones 2011-07-14 11:47:53 -07:00
hpet.c Merge branch 'driver-core-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core 2012-01-07 12:03:30 -08:00
hw_breakpoint.c x86: Use this_cpu_ops to optimize code 2010-12-30 12:20:28 +01:00
i386_ksyms_32.c
i387.c i387: ptrace breaks the lazy-fpu-restore logic 2012-04-16 16:23:59 -07:00
i8237.c x86: Use syscore_ops instead of sysdev classes and sysdevs 2011-03-23 22:15:54 +01:00
i8253.c x86: Use common i8253 clockevent 2011-07-01 10:37:14 +02:00
i8259.c Disintegrate asm/system.h for X86 2012-03-28 18:11:12 +01:00
init_task.c
io_delay.c
ioport.c x86: Use bitmap library functions 2011-02-17 14:59:22 +01:00
irq_32.c x86-32/irq: Don't switch to irq stack for a user-mode irq 2012-02-20 09:30:18 +01:00
irq_64.c x86: Add stack top margin for stack overflow checking 2011-12-07 09:27:11 +01:00
irq_work.c
irq.c x86: Preserve lazy irq disable semantics in fixup_irqs() 2012-03-29 15:28:47 +02:00
irqinit.c Merge branch 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-03-29 18:21:35 -07:00
jump_label.c jump_label, x86: Fix section mismatch 2011-12-06 20:41:02 +01:00
kdebugfs.c simple_open: automatically convert to simple_open() 2012-04-05 15:25:50 -07:00
kgdb.c KGDB/KDB regression fixes 2012-04-04 17:26:08 -07:00
kprobes-common.h x86/kprobes: Split out optprobe related code to kprobes-opt.c 2012-03-06 09:49:49 +01:00
kprobes-opt.c x86/kprobes: Split out optprobe related code to kprobes-opt.c 2012-03-06 09:49:49 +01:00
kprobes.c x86/kprobes: Split out optprobe related code to kprobes-opt.c 2012-03-06 09:49:49 +01:00
kvm.c KVM: Resolve RCU vs. async page fault problem 2012-04-05 19:26:14 +03:00
kvmclock.c x86: kvmclock: abstract save/restore sched_clock_state 2012-03-20 12:37:45 +02:00
ldt.c Disintegrate asm/system.h for X86 2012-03-28 18:11:12 +01:00
machine_kexec_32.c Disintegrate asm/system.h for X86 2012-03-28 18:11:12 +01:00
machine_kexec_64.c
Makefile x86/kprobes: Split out optprobe related code to kprobes-opt.c 2012-03-06 09:49:49 +01:00
mca_32.c Disintegrate asm/system.h for X86 2012-03-28 18:11:12 +01:00
microcode_amd.c x86, microcode: Ensure that module is only loaded on supported AMD CPUs 2012-04-13 11:51:05 +02:00
microcode_core.c x86, microcode: Ensure that module is only loaded on supported AMD CPUs 2012-04-13 11:51:05 +02:00
microcode_intel.c x86, intel: Output microcode revision in /proc/cpuinfo 2011-10-14 13:16:35 +02:00
mmconf-fam10h_64.c
module.c Disintegrate asm/system.h for X86 2012-03-28 18:11:12 +01:00
mpparse.c Merge branch 'memblock-kill-early_node_map' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc into core/memblock 2011-12-20 12:14:26 +01:00
msr.c Disintegrate asm/system.h for X86 2012-03-28 18:11:12 +01:00
nmi_selftest.c x86: Properly _init-annotate NMI selftest code 2012-02-27 08:43:37 +01:00
nmi.c x86: Allow NMIs to hit breakpoints in i386 2011-12-21 15:38:55 -05:00
paravirt_patch_32.c
paravirt_patch_64.c
paravirt-spinlocks.c
paravirt.c Disintegrate and delete asm/system.h 2012-03-28 15:58:21 -07:00
pci-calgary_64.c Merge branch 'for-linus' of git://git.linaro.org/people/mszyprowski/linux-dma-mapping 2012-04-04 17:13:43 -07:00
pci-dma.c Merge branch 'for-linus' of git://git.linaro.org/people/mszyprowski/linux-dma-mapping 2012-04-04 17:13:43 -07:00
pci-iommu_table.c arch/x86/kernel/pci-iommu_table.c: Convert sprintf_symbol to %pS 2011-05-10 10:21:35 +02:00
pci-nommu.c X86 & IA64: adapt for dma_map_ops changes 2012-03-28 16:36:31 +02:00
pci-swiotlb.c X86 & IA64: adapt for dma_map_ops changes 2012-03-28 16:36:31 +02:00
pcspeaker.c
probe_roms.c x86: Include probe_roms.h in probe_roms.c 2012-03-08 10:57:35 +01:00
process_32.c Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-03-29 14:28:26 -07:00
process_64.c IA32 emulation: Fix build problem for modular ia32 a.out support 2012-05-06 18:26:20 -07:00
process.c x86/sched: Make mwait_usable() heed to "idle=" kernel parameters properly 2012-05-07 16:27:20 +02:00
ptrace.c Merge branch 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-03-29 18:21:35 -07:00
pvclock.c
quirks.c x86, amd: Fix up numa_node information for AMD CPU family 15h model 0-0fh northbridge functions 2011-12-05 18:13:11 +01:00
reboot_32.S x86, reboot: Fix relocations in reboot_32.S 2011-05-02 14:44:46 -07:00
reboot_fixups_32.c
reboot.c x86/reboot: Remove VersaLogic Menlow reboot quirk 2012-01-30 10:52:33 +01:00
relocate_kernel_32.S kexec, x86: Fix incorrect jump back address if not preserving context 2011-07-21 11:19:28 +02:00
relocate_kernel_64.S kexec, x86: Fix incorrect jump back address if not preserving context 2011-07-21 11:19:28 +02:00
resource.c x86: avoid high BIOS area when allocating address space 2010-12-17 10:01:30 -08:00
rtc.c x86/rtc, mrst: Don't register a platform RTC device for for Intel MID platforms 2011-12-05 17:09:21 +01:00
setup_percpu.c x86: Unify CPU -> NUMA node mapping between 32 and 64bit 2011-01-28 14:54:09 +01:00
setup.c Merge branch 'akpm' (Andrew's patch-bomb) 2012-03-28 17:19:28 -07:00
signal.c Merge branch 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-03-29 18:21:35 -07:00
smp.c x86, reboot: Fix typo in nmi reboot path 2012-01-07 12:19:37 +01:00
smpboot.c Merge branch 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux 2012-03-30 16:45:39 -07:00
stacktrace.c x86: Swap save_stack_trace_regs parameters 2011-06-14 22:48:51 -04:00
step.c x86-64: Add user_64bit_mode paravirt op 2011-08-04 16:13:49 -07:00
sys_i386_32.c
sys_x86_64.c Merge branch 'x86-x32-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-03-29 18:12:23 -07:00
syscall_32.c x86, syscall: Re-fix typo in comment 2011-11-18 16:25:07 -08:00
syscall_64.c x32: If configured, add x32 system calls to system call tables 2012-02-20 12:52:06 -08:00
tboot.c tboot: Add return values for tboot_sleep 2012-03-13 14:06:55 -04:00
tce_64.c Disintegrate asm/system.h for X86 2012-03-28 18:11:12 +01:00
test_nx.c x86: Eliminate various 'set but not used' warnings 2011-05-21 19:10:33 +02:00
test_rodata.c
time.c x86/time: Eliminate unused irq0_irqs counter 2012-02-27 08:46:25 +01:00
tls.c Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-03-29 14:28:26 -07:00
tls.h
topology.c x86: Fix files explicitly requiring export.h for EXPORT_SYMBOL/THIS_MODULE 2011-10-31 19:30:35 -04:00
trampoline_32.S x86, trampoline: Common infrastructure for low memory trampolines 2011-02-17 21:02:43 -08:00
trampoline_64.S x86-64, trampoline: Remove unused variable 2011-02-18 15:50:36 -08:00
trampoline.c memblock, x86: Replace memblock_x86_reserve/free_range() with generic ones 2011-07-14 11:47:53 -07:00
traps.c Merge branch 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-03-29 18:21:35 -07:00
tsc_sync.c x86/tsc: Reduce the TSC sync check time for core-siblings 2012-02-22 11:49:40 +01:00
tsc.c Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-03-29 14:16:48 -07:00
verify_cpu.S x86: Fix common misspellings 2011-03-18 10:39:30 +01:00
vm86_32.c Merge branch 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-03-29 18:21:35 -07:00
vmlinux.lds.S x86-64: Rework vsyscall emulation and add vsyscall= parameter 2011-08-10 19:26:46 -05:00
vsmp_64.c
vsyscall_64.c x86: vsyscall: Use NULL instead 0 for a pointer argument 2012-04-06 11:49:59 +02:00
vsyscall_emu_64.S x86-64: Rework vsyscall emulation and add vsyscall= parameter 2011-08-10 19:26:46 -05:00
vsyscall_trace.h x86-64: Add vsyscall:emulate_vsyscall trace event 2011-08-04 16:13:53 -07:00
x86_init.c x86/platform: Remove incorrect error message in x86_default_fixup_cpu_id() 2012-04-16 20:43:43 +02:00
x8664_ksyms_64.c x86-64, mem: Convert memmove() to assembly file and fix return value bug 2011-01-25 16:58:39 -08:00
xsave.c i387: Split up <asm/i387.h> into exported and internal interfaces 2012-02-21 14:12:54 -08:00