Commit Graph

8 Commits

Author SHA1 Message Date
Ingo Molnar
5ee613b675 x86: idle wakeup event in the HLT loop
do a proper idle-wakeup event on HLT as well - some CPUs stop the TSC
in HLT too, not just when going through the ACPI methods.

(the ACPI idle code already does this.)

[ update the 64-bit side too, as noticed by Jiri Slaby. ]

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:30:06 +01:00
Steven Rostedt
40d6a14662 Kick CPUS that might be sleeping in cpus_idle_wait
Sometimes cpu_idle_wait gets stuck because it might miss CPUS that are
already in idle, have no tasks waiting to run and have no interrupts going
to them.  This is common on bootup when switching cpu idle governors.

This patch gives those CPUS that don't check in an IPI kick.

 Background:
 -----------
I notice this while developing the mcount patches, that every once in a
while the system would hang. Looking deeper, the hang was always at boot
up when registering init_menu of the cpu_idle menu governor. Talking
with Thomas Gliexner, we discovered that one of the CPUS had no timer
events scheduled for it and it was in idle (running with NO_HZ). So the
CPU would not set the cpu_idle_state bit.

Hitting sysrq-t a few times would eventually route the interrupt to the
stuck CPU and the system would continue.

Note, I would have used the PDA isidle but that is set after the
cpu_idle_state bit is cleared, and would leave a window open where we
may miss being kicked.

hmm, looking closer at this, we still have a small race window between
clearing the cpu_idle_state and disabling interrupts (hence the RFC).

    CPU0:                          CPU 1:
  ---------                       ---------
 cpu_idle_wait():                 cpu_idle():
      |                           __cpu_cpu_var(is_idle) = 1;
      |                           if (__get_cpu_var(cpu_idle_state)) /* == 0 */
 per_cpu(cpu_idle_state, 1) = 1;         |
 if (per_cpu(is_idle, 1)) /* == 1 */     |
 smp_call_function(1)                    |
      |                             receives ipi and runs do_nothing.
 wait on map == empty               idle();
   /* waits forever */

So really we need interrupts off for most of this then. One might think
that we could simply clear the cpu_idle_state from do_nothing, but I'm
assuming that cpu_idle governors can be removed, and this might cause a
race that a governor might be used after the module was removed.

Venki said:

  I think your RFC patch is the right solution here.  As I see it, there is
  no race with your RFC patch.  As long as you call a dummy smp_call_function
  on all CPUs, we should be OK.  We can get rid of cpu_idle_state and the
  current wait forever logic altogether with dummy smp_call_function.  And so
  there wont be any wait forever scenario.

  The whole point of cpu_idle_wait() is to make all CPUs come out of idle
  loop atleast once.  The caller will use cpu_idle_wait something like this.

  // Want to change idle handler

  - Switch global idle handler to always present default_idle

  - call cpu_idle_wait so that all cpus come out of idle for an instant
    and stop using old idle pointer and start using default idle

  - Change the idle handler to a new handler

  - optional cpu_idle_wait if you want all cpus to start using the new
    handler immediately.

Maybe the below 1s patch is safe bet for .24.  But for .25, I would say we
just replace all complicated logic by simple dummy smp_call_function and
remove cpu_idle_state altogether.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andi Kleen <ak@suse.de>
Cc: Len Brown <lenb@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-01-14 08:52:22 -08:00
Adrian Bunk
3446fa057c x86_32: select_idle_routine() must be __cpuinit
CONFIG_HOTPLUG_CPU=y:

WARNING: vmlinux.o(.text+0x1199a): Section mismatch: reference to .init.text.5:select_idle_routine (between 'init_intel' and 'init_nexgen')

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2007-12-19 23:20:18 +01:00
Linus Torvalds
60812a4a99 Merge ssh://master.kernel.org/pub/scm/linux/kernel/git/tglx/linux-2.6-x86
* ssh://master.kernel.org/pub/scm/linux/kernel/git/tglx/linux-2.6-x86: (33 commits)
  x86: convert cpuinfo_x86 array to a per_cpu array
  x86: introduce frame_pointer() and stack_pointer()
  x86 & generic: change to __builtin_prefetch()
  i386: do not BUG_ON() when MSR is unknown
  x86: acpi use cpu_physical_id
  x86: convert cpu_llc_id to be a per cpu variable
  x86: convert cpu_to_apicid to be a per cpu variable
  i386: introduce "used_vectors" bitmap which can be used to reserve vectors.
  x86: use raw locks during oopses
  x86: honor _PAGE_PSE bit on page walks
  i386: do cpuid_device_create() in CPU_UP_PREPARE instead of CPU_ONLINE.
  x86: implement missing x86_64 function smp_call_function_mask()
  x86: use descriptor's functions instead of inline assembly
  i386: consolidate show_regs and show_registers for i386
  i386: make callgraph use dump_trace() on i386/x86_64
  x86: enable iommu_merge by default
  i386: i386 add AMD64 Barcelona PMU MSR definitions to msr.h
  x86: Unify i386 and x86-64 early quirks
  x86: enable HPET on ICH3 and ICH4
  x86: force enable HPET on VT8235/8237 chipsets
  ...

Manually fix trivial conflict with task pid container helper changes in
arch/x86/kernel/process_32.c
2007-10-19 15:06:00 -07:00
Alexey Dobriyan
19c5870c0e Use helpers to obtain task pid in printks (arch code)
One of the easiest things to isolate is the pid printed in kernel log.
There was a patch, that made this for arch-independent code, this one makes
so for arch/xxx files.

It took some time to cross-compile it, but hopefully these are all the
printks in arch code.

Signed-off-by: Alexey Dobriyan <adobriyan@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 11:53:43 -07:00
Pavel Emelyanov
9d975ebda5 i386: consolidate show_regs and show_registers for i386
Both functions printk the same information, except for CRx and
debug registers in the show_registers() one and a bit different
manner. So move the common code into one place. This is already
done for x86_64, so I think it's worth having the same on i386.

This saves 100 bytes of .rodata section :) ...
   but only 8 from .text :(

[ tglx: arch/x86 adaptation ]

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-19 20:35:03 +02:00
Dave Jones
835c34a168 Delete filenames in comments.
Since the x86 merge, lots of files that referenced their own filenames
are no longer correct.  Rather than keep them up to date, just delete
them, as they add no real value.

Additionally:
- fix up comment formatting in scx200_32.c
- Remove a credit from myself in setup_64.c from a time when we had no SCM
- remove longwinded history from tsc_32.c which can be figured out from
  git.

Signed-off-by: Dave Jones <davej@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-13 10:01:23 -07:00
Thomas Gleixner
9a163ed8e0 i386: move kernel
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-11 11:17:01 +02:00