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5fbd036b55
linux/arch/arm/kernel
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Peter Zijlstra 5fbd036b55 sched: Cleanup cpu_active madness 
Stepan found:

CPU0		CPUn

_cpu_up()
  __cpu_up()

		boostrap()
		  notify_cpu_starting()
		  set_cpu_online()
		  while (!cpu_active())
		    cpu_relax()

<PREEMPT-out>

smp_call_function(.wait=1)
  /* we find cpu_online() is true */
  arch_send_call_function_ipi_mask()

  /* wait-forever-more */

<PREEMPT-in>
		  local_irq_enable()

  cpu_notify(CPU_ONLINE)
    sched_cpu_active()
      set_cpu_active()

Now the purpose of cpu_active is mostly with bringing down a cpu, where
we mark it !active to avoid the load-balancer from moving tasks to it
while we tear down the cpu. This is required because we only update the
sched_domain tree after we brought the cpu-down. And this is needed so
that some tasks can still run while we bring it down, we just don't want
new tasks to appear.

On cpu-up however the sched_domain tree doesn't yet include the new cpu,
so its invisible to the load-balancer, regardless of the active state.
So instead of setting the active state after we boot the new cpu (and
consequently having to wait for it before enabling interrupts) set the
cpu active before we set it online and avoid the whole mess.

Reported-by: Stepan Moskovchenko <stepanm@codeaurora.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1323965362.18942.71.camel@twins
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2012-03-12 20:43:15 +01:00
..
.gitignore
armksyms.c arm: convert core files from module.h to export.h 2011-10-31 19:30:49 -04:00
arthur.c
asm-offsets.c ARM: 7114/1: cache-l2x0: add resume entry for l2 in secure mode 2011-10-17 09:11:51 +01:00
atags.c
atags.h
bios32.c arm/PCI: convert to pci_scan_root_bus() for correct root bus resources 2012-01-06 12:10:56 -08:00
calls.S ARM: wire up process_vm_writev and process_vm_readv syscalls 2011-11-17 16:58:00 +00:00
compat.c ARM: deprecate support for old way to pass kernel parameters 2010-07-07 16:38:36 +02:00
compat.h ARM: deprecate support for old way to pass kernel parameters 2010-07-07 16:38:36 +02:00
crash_dump.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
crunch-bits.S
crunch.c ARM: Convert VFP/Crunch/XscaleCP thread_release() to exit_thread() 2009-12-18 14:53:41 +00:00
debug.S Merge branch 'devel-stable' of http://ftp.arm.linux.org.uk/pub/linux/arm/kernel/git-cur/linux-2.6-arm 2011-10-28 12:02:27 -07:00
devtree.c arm: convert core files from module.h to export.h 2011-10-31 19:30:49 -04:00
dma-isa.c ARM: dma-isa: request cascade channel after registering it 2009-12-24 18:34:08 +00:00
dma.c locking, ARM: Annotate low level hw locks as raw 2011-09-13 11:12:14 +02:00
early_printk.c ARM: Add an earlyprintk debug console 2009-12-09 10:02:18 +00:00
ecard.c ARM: io: RiscPC: make EASI_BASE a void iomem pointer 2011-08-17 08:44:16 +01:00
ecard.h
elf.c arm: convert core files from module.h to export.h 2011-10-31 19:30:49 -04:00
entry-armv.S ARM: 7314/1: kuser: consistently use usr_ret for returning from helpers 2012-02-03 15:58:46 +00:00
entry-common.S ARM: 7299/1: ftrace: clear zero bit in reported IPs for Thumb-2 2012-01-25 09:24:37 +00:00
entry-header.S Merge branch 'devel-stable' into for-next 2011-07-22 23:09:07 +01:00
etm.c arm: fix implicit module.h users by adding it to arch/arm as required. 2011-10-31 19:30:50 -04:00
fiq.c ARM: 6938/1: fiq: Refactor {get,set}_fiq_regs() for Thumb-2 2011-05-26 10:31:06 +01:00
fiqasm.S ARM: 6938/1: fiq: Refactor {get,set}_fiq_regs() for Thumb-2 2011-05-26 10:31:06 +01:00
ftrace.c ARM: ftrace: graph tracer + dynamic ftrace 2010-11-19 21:43:27 +05:30
head-common.S arm/dt: Make __vet_atags also accept a dtb image 2011-05-11 15:12:32 +02:00
head-nommu.S ARM: 6999/1: head, zImage: Always Enter the kernel in ARM state 2011-07-19 12:00:53 +01:00
head.S ARM: 7275/1: LPAE: Check the CPU support for the long descriptor format 2012-01-13 08:56:41 +00:00
hw_breakpoint.c ARM: LPAE: Add fault handling support 2011-12-08 10:30:40 +00:00
init_task.c Use new __init_task_data macro in arch init_task.c files. 2009-09-21 06:27:08 +02:00
io.c arm: convert core files from module.h to export.h 2011-10-31 19:30:49 -04:00
irq.c arm: remove several unnecessary module.h include instances 2011-10-31 19:30:48 -04:00
isa.c sysctl: Drop & in front of every proc_handler. 2009-11-18 08:37:40 -08:00
iwmmxt.S ARM: pxa: fix logic error in PJ4 iWMMXt handling 2011-08-11 10:10:26 +08:00
kgdb.c kgdb,arm: fix register dump 2010-10-29 13:14:40 -05:00
kprobes-arm.c ARM: 7181/1: Restrict kprobes probing SWP instructions to ARMv5 and below 2011-11-30 23:54:54 +00:00
kprobes-common.c ARM: kprobes: Add alu_write_pc() 2011-07-13 17:32:48 +00:00
kprobes-test-arm.c ARM: 7181/1: Restrict kprobes probing SWP instructions to ARMv5 and below 2011-11-30 23:54:54 +00:00
kprobes-test-thumb.c ARM: 7174/1: Fix build error in kprobes test code on Thumb2 kernels 2011-11-26 21:58:53 +00:00
kprobes-test.c ARM: 7209/1: Use generic ARM instruction set condition code checks for kprobes. 2011-12-13 08:52:03 +00:00
kprobes-test.h ARM: 7174/1: Fix build error in kprobes test code on Thumb2 kernels 2011-11-26 21:58:53 +00:00
kprobes-thumb.c ARM: kprobes: Add exports for test code 2011-09-20 18:17:43 +00:00
kprobes.c ARM: kprobes: Extend arch_specific_insn to add pointer to emulated instruction 2011-07-13 17:32:42 +00:00
kprobes.h ARM: kprobes: Add exports for test code 2011-09-20 18:17:43 +00:00
leds.c arm: leds: convert sysdev_class to a regular subsystem 2011-12-21 15:52:57 -08:00
machine_kexec.c Merge branch 'restart-cleanup' into restart 2012-01-05 12:56:44 +00:00
Makefile ARM: 7206/1: Add generic ARM instruction set condition code checks. 2011-12-13 08:52:02 +00:00
module.c ARM: 7059/1: LPAE: Use PMD_(SHIFT|SIZE|MASK) instead of PGDIR_* 2011-08-23 15:30:33 +01:00
opcodes.c ARM: 7206/1: Add generic ARM instruction set condition code checks. 2011-12-13 08:52:02 +00:00
perf_event_v6.c ARM: perf: add support for stalled cycle ABI events 2011-12-02 15:16:16 +00:00
perf_event_v7.c ARM: 7303/1: perf: add empty NODE event definitions for Cortex-A5 and Cortex-A15 2012-02-02 17:37:42 +00:00
perf_event_xscale.c ARM: perf: add support for stalled cycle ABI events 2011-12-02 15:16:16 +00:00
perf_event.c Merge branch 'devel-stable' into for-linus 2012-01-05 13:24:33 +00:00
pj4-cp0.c arm: remove several unnecessary module.h include instances 2011-10-31 19:30:48 -04:00
pmu.c ARM: PMU: re-export release_pmu symbol to modules 2011-11-16 10:06:42 +00:00
process.c sched/rt: Use schedule_preempt_disabled() 2012-03-01 10:28:03 +01:00
ptrace.c ARM/audit: include audit header and fix audit arch 2012-02-21 16:50:14 +00:00
relocate_kernel.S ARM: 7065/1: kexec: ensure new kernel is entered in ARM state 2011-08-28 10:39:41 +01:00
return_address.c arm: convert core files from module.h to export.h 2011-10-31 19:30:49 -04:00
sched_clock.c ARM: 7205/2: sched_clock: allow sched_clock to be selected at runtime 2011-12-18 23:00:26 +00:00
setup.c ARM: 7293/1: logical_cpu_map: decouple CPU mapping from SMP 2012-01-23 10:20:05 +00:00
signal.c ARM: 7306/1: vfp: flush thread hwstate before restoring context from sigframe 2012-02-02 17:37:41 +00:00
signal.h ARM: Fix signal restart issues with NX and OABI compat 2009-10-25 15:39:37 +00:00
sleep.S ARM: LPAE: add ISBs around MMU enabling code 2011-12-08 10:30:38 +00:00
smp_scu.c Merge branches 'arnd-randcfg-fixes', 'debug', 'io' (early part), 'l2x0', 'p2v', 'pgt' (early part) and 'smp' into for-linus 2011-10-25 08:19:29 +01:00
smp_tlb.c ARM: SMP: split out software TLB maintainence broadcasting 2010-12-20 15:09:17 +00:00
smp_twd.c ARM: 7336/1: smp_twd: Don't register CPUFREQ notifiers if local timers are not initialised 2012-02-21 09:26:46 +00:00
smp.c sched: Cleanup cpu_active madness 2012-03-12 20:43:15 +01:00
stacktrace.c arm: convert core files from module.h to export.h 2011-10-31 19:30:49 -04:00
suspend.c ARM: suspend: use idmap_pgd instead of suspend_pgd 2011-12-06 14:04:14 +00:00
swp_emulate.c ARM: 7208/1: Add condition code checking to SWP emulation handler. 2011-12-13 08:52:03 +00:00
sys_arm.c arm: convert core files from module.h to export.h 2011-10-31 19:30:49 -04:00
sys_oabi-compat.c ARM: 6891/1: prevent heap corruption in OABI semtimedop 2011-04-29 15:53:14 +01:00
tcm.c ARM: 7199/2: only look for TCM on ARMv5 and later 2011-12-13 08:52:02 +00:00
tcm.h ARM: 5580/2: ARM TCM (Tightly-Coupled Memory) support v3 2009-09-15 22:11:05 +01:00
thumbee.c Fix the teehbr_read function prototype 2008-11-10 14:14:11 +00:00
time.c arm: convert core files from module.h to export.h 2011-10-31 19:30:49 -04:00
topology.c ARM: 7182/1: ARM cpu topology: fix warning 2011-11-30 23:55:21 +00:00
traps.c ARM: 7322/1: Print BUG instead of undefined instruction on BUG_ON() 2012-02-09 16:25:37 +00:00
unwind.c ARM: unwinder: fix bisection to find origin in .idx section 2011-12-15 14:02:19 -08:00
vmlinux.lds.S ARM: 7320/1: Fix proc_info table alignment 2012-02-09 16:25:37 +00:00
xscale-cp0.c arm: remove several unnecessary module.h include instances 2011-10-31 19:30:48 -04:00