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apic.h does not get included on UP compiles. That way the
APICTIMER_STOPS_ON_C3 is not there and UP boxen have no support for timer
broadcasting. This was never noticed, because the lapic timer is only used
for profiling on UP.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Len Brown <len.brown@intel.com>
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drivers/acpi/namespace/nsparse.c:126: warning: int format, different type arg (arg 7)
drivers/acpi/tables/tbfadt.c:224: warning: unsigned int format, different type arg (arg 6)
drivers/acpi/utilities/utdebug.c:184: warning: cast from pointer to integer of different size
drivers/acpi/utilities/utdebug.c:184: warning: cast from pointer to integer of different size
drivers/acpi/utilities/utdebug.c:197: warning: cast from pointer to integer of different size
drivers/acpi/processor_idle.c:1093: warning: long long unsigned int format, u64 arg (arg 5)
Signed-off-by: Len Brown <len.brown@intel.com>
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Signed-off-by: Len Brown <len.brown@intel.com>
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Remove flags parameter for acpi_{get,set}_register().
It is no longer necessary now that these functions use a
spinlock for mutual exclusion.
Signed-off-by: Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
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Signed-off-by: Len Brown <len.brown@intel.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-acpi-2.6
* 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-acpi-2.6: (68 commits)
ACPI: replace kmalloc+memset with kzalloc
ACPI: Add support for acpi_load_table/acpi_unload_table_id
fbdev: update after backlight argument change
ACPI: video: Add dev argument for backlight_device_register
ACPI: Implement acpi_video_get_next_level()
ACPI: Kconfig - depend on PM rather than selecting it
ACPI: fix NULL check in drivers/acpi/osl.c
ACPI: make drivers/acpi/ec.c:ec_ecdt static
ACPI: prevent processor module from loading on failures
ACPI: fix single linked list manipulation
ACPI: ibm_acpi: allow clean removal
ACPI: fix git automerge failure
ACPI: ibm_acpi: respond to workqueue update
ACPI: dock: add uevent to indicate change in device status
ACPI: ec: Lindent once again
ACPI: ec: Change #define to enums there possible.
ACPI: ec: Style changes.
ACPI: ec: Acquire Global Lock under EC mutex.
ACPI: ec: Drop udelay() from poll mode. Loop by reading status field instead.
ACPI: ec: Rename gpe_bit to gpe
...
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APM idle code
Fernando Lopez-Lezcano reported frequent scheduling latencies and audio
xruns starting at the 2.6.18-rt kernel, and those problems persisted all
until current -rt kernels. The latencies were serious and unjustified by
system load, often in the milliseconds range.
After a patient and heroic multi-month effort of Fernando, where he
tested dozens of kernels, tried various configs, boot options,
test-patches of mine and provided latency traces of those incidents, the
following 'smoking gun' trace was captured by him:
_------=> CPU#
/ _-----=> irqs-off
| / _----=> need-resched
|| / _---=> hardirq/softirq
||| / _--=> preempt-depth
|||| /
||||| delay
cmd pid ||||| time | caller
\ / ||||| \ | /
IRQ_19-1479 1D..1 0us : __trace_start_sched_wakeup (try_to_wake_up)
IRQ_19-1479 1D..1 0us : __trace_start_sched_wakeup <<...>-5856> (37 0)
IRQ_19-1479 1D..1 0us : __trace_start_sched_wakeup (c01262ba 0 0)
IRQ_19-1479 1D..1 0us : resched_task (try_to_wake_up)
IRQ_19-1479 1D..1 0us : __spin_unlock_irqrestore (try_to_wake_up)
...
<idle>-0 1...1 11us!: default_idle (cpu_idle)
...
<idle>-0 0Dn.1 602us : smp_apic_timer_interrupt (c0103baf 1 0)
...
<...>-5856 0D..2 618us : __switch_to (__schedule)
<...>-5856 0D..2 618us : __schedule <<idle>-0> (20 162)
<...>-5856 0D..2 619us : __spin_unlock_irq (__schedule)
<...>-5856 0...1 619us : trace_stop_sched_switched (__schedule)
<...>-5856 0D..1 619us : trace_stop_sched_switched <<...>-5856> (37 0)
what is visible in this trace is that CPU#1 ran try_to_wake_up() for
PID:5856, it placed PID:5856 on CPU#0's runqueue and ran resched_task()
for CPU#0. But it decided to not send an IPI that no CPU - due to
TS_POLLING. But CPU#0 never woke up after its NEED_RESCHED bit was set,
and only rescheduled to PID:5856 upon the next lapic timer IRQ. The
result was a 600+ usecs latency and a missed wakeup!
the bug turned out to be an idle-wakeup bug introduced into the mainline
kernel this summer via an optimization in the x86_64 tree:
commit 495ab9c045e1b0e5c82951b762257fe1c9d81564
Author: Andi Kleen <ak@suse.de>
Date: Mon Jun 26 13:59:11 2006 +0200
[PATCH] i386/x86-64/ia64: Move polling flag into thread_info_status
During some profiling I noticed that default_idle causes a lot of
memory traffic. I think that is caused by the atomic operations
to clear/set the polling flag in thread_info. There is actually
no reason to make this atomic - only the idle thread does it
to itself, other CPUs only read it. So I moved it into ti->status.
the problem is this type of change:
if (!hlt_counter && boot_cpu_data.hlt_works_ok) {
- clear_thread_flag(TIF_POLLING_NRFLAG);
+ current_thread_info()->status &= ~TS_POLLING;
smp_mb__after_clear_bit();
while (!need_resched()) {
local_irq_disable();
this changes clear_thread_flag() to an explicit clearing of TS_POLLING.
clear_thread_flag() is defined as:
clear_bit(flag, &ti->flags);
and clear_bit() is a LOCK-ed atomic instruction on all x86 platforms:
static inline void clear_bit(int nr, volatile unsigned long * addr)
{
__asm__ __volatile__( LOCK_PREFIX
"btrl %1,%0"
hence smp_mb__after_clear_bit() is defined as a simple compile barrier:
#define smp_mb__after_clear_bit() barrier()
but the explicit TS_POLLING clearing introduced by the patch:
+ current_thread_info()->status &= ~TS_POLLING;
is not an atomic op! So the clearing of the TS_POLLING bit is freely
reorderable with the reading of the NEED_RESCHED bit - and both now
reside in different memory addresses.
CPU idle wakeup very much depends on ordered memory ops, the clearing of
the TS_POLLING flag must always be done before we test need_resched()
and hit the idle instruction(s). [Symmetrically, the wakeup code needs
to set NEED_RESCHED before it tests the TS_POLLING flag, so memory
ordering is paramount.]
Fernando's dual-core Athlon64 system has a sufficiently advanced memory
ordering model so that it triggered this scenario very often.
( And it also turned out that the reason why these latencies never
triggered on my testsystems is that i routinely use idle=poll, which
was the only idle variant not affected by this bug. )
The fix is to change the smp_mb__after_clear_bit() to an smp_mb(), to
act as an absolute barrier between the TS_POLLING write and the
NEED_RESCHED read. This affects almost all idling methods (default,
ACPI, APM), on all 3 x86 architectures: i386, x86_64, ia64.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Tested-by: Fernando Lopez-Lezcano <nando@ccrma.Stanford.EDU>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Conflicts:
drivers/acpi/button.c
drivers/acpi/ec.c
drivers/acpi/osl.c
drivers/acpi/sbs.c
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This patch breaks C-state discovery on my IBM IntelliStation Z30 because
the return value of acpi_processor_get_power_info_fadt is not assigned to
"result" in the case that acpi_processor_get_power_info_cst returns
-ENODEV. Thus, if ACPI provides C-state data via the FADT and not _CST (as
is the case on this machine), we incorrectly exit the function with -ENODEV
after reading the FADT. The attached patch sets the value of result so
that we don't exit early.
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Acked-by: "Pallipadi, Venkatesh" <venkatesh.pallipadi@intel.com>
Acked-by: "Brown, Len" <len.brown@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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drivers/acpi/processor_idle.c:1112: warning: 'smp_callback' defined but not used
Cc: Len Brown <lenb@kernel.org>
Cc: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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The ACPI processor init functions should be marked as __cpuinit as they use
structures marked with __cpuinitdata.
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Len Brown <len.brown@intel.com>
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Signed-off-by: Jan Engelhardt <jengelh@gmx.de>
Signed-off-by: Len Brown <len.brown@intel.com>
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Intel processors starting with the Core Duo support
support processor native C-state using the MWAIT instruction.
Refer: Intel Architecture Software Developer's Manual
http://www.intel.com/design/Pentium4/manuals/253668.htm
Platform firmware exports the support for Native C-state to OS using
ACPI _PDC and _CST methods.
Refer: Intel Processor Vendor-Specific ACPI: Interface Specification
http://www.intel.com/technology/iapc/acpi/downloads/302223.htm
With Processor Native C-state, we use 'MWAIT' instruction on the processor
to enter different C-states (C1, C2, C3). We won't use the special IO
ports to enter C-state and no SMM mode etc required to enter C-state.
Overall this will mean better C-state support.
One major advantage of using MWAIT for all C-states is, with this and
"treat interrupt as break event" feature of MWAIT, we can now get accurate
timing for the time spent in C1, C2, .. states.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Len Brown <len.brown@intel.com>
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Add infrastructure to track "maximum allowable latency" for power saving
policies.
The reason for adding this infrastructure is that power management in the
idle loop needs to make a tradeoff between latency and power savings
(deeper power save modes have a longer latency to running code again). The
code that today makes this tradeoff just does a rather simple algorithm;
however this is not good enough: There are devices and use cases where a
lower latency is required than that the higher power saving states provide.
An example would be audio playback, but another example is the ipw2100
wireless driver that right now has a very direct and ugly acpi hook to
disable some higher power states randomly when it gets certain types of
error.
The proposed solution is to have an interface where drivers can
* announce the maximum latency (in microseconds) that they can deal with
* modify this latency
* give up their constraint
and a function where the code that decides on power saving strategy can
query the current global desired maximum.
This patch has a user of each side: on the consumer side, ACPI is patched
to use this, on the producer side the ipw2100 driver is patched.
A generic maximum latency is also registered of 2 timer ticks (more and you
lose accurate time tracking after all).
While the existing users of the patch are x86 specific, the infrastructure
is not. I'd like to ask the arch maintainers of other architectures if the
infrastructure is generic enough for their use (assuming the architecture
has such a tradeoff as concept at all), and the sound/multimedia driver
owners to look at the driver facing API to see if this is something they
can use.
[akpm@osdl.org: cleanups]
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Jesse Barnes <jesse.barnes@intel.com>
Cc: "Brown, Len" <len.brown@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
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Signed-off-by: Len Brown <len.brown@intel.com>
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Signed-off-by: Len Brown <len.brown@intel.com>
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While trying to look for superfluous I/O accesses that can be optimized
away, I stumbled upon this ACPI sleep I/O access and couldn't figure out
why the hell this dummy op was necessary.
After more than one hour of internet research, I had collected a sufficient
number of documents (among those very old kernel versions) that finally
told me what this dummy read was about: STPCLK# doesn't get asserted in time
on (some) chipsets, which is why we need to have a dummy I/O read to delay
further instruction processing until the CPU is fully stopped.
Signed-off-by: Andreas Mohr <andi@lisas.de>
Signed-off-by: Len Brown <len.brown@intel.com>
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Only if bus master activity is going on at the present, we should avoid
entering C3-type sleep, as it might be a faulty transition. As long as the
bm_activity bitmask was based on the number of calls to the ACPI idle
function, looking at previous moments made sense. Now, with it being based on
what happened this jiffy, looking at this jiffy should be sufficient.
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Len Brown <len.brown@intel.com>
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Do not assume there was bus mastering activity if the idle handler didn't get
called, as there's only reason to not enter C3-type sleep if there is bus
master activity going on. Only for the "promotion" into C3-type sleep bus
mastering activity is taken into account, and there only current bus mastering
activity, and not pure guessing should lead to the decision on whether to
enter C3-type sleep or not.
Also, as bm_activity is a jiffy-based bitmask (bit 0: bus mastering activity
during this juffy, bit 31: bus mastering activity 31 jiffies ago), fix the
setting of bit 0, as it might be called multiple times within one jiffy.
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Len Brown <len.brown@intel.com>
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Track the actual time spent in C-States (C2 upwards, we can't determine this
for C1), not only the number of invocations. This is especially useful for
dynamic ticks / "tickless systems", but is also of interest on normal systems,
as any interrupt activity leads to C-States being exited, not only the timer
interrupt.
The time is being measured in PM timer ticks, so an increase by one equals 279
nanoseconds.
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Len Brown <len.brown@intel.com>
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Signed-off-by: Len Brown <len.brown@intel.com>
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Signed-off-by: Len Brown <len.brown@intel.com>
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Signed-off-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>
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* x86-64: (83 commits)
[PATCH] x86_64: x86_64 stack usage debugging
[PATCH] x86_64: (resend) x86_64 stack overflow debugging
[PATCH] x86_64: msi_apic.c build fix
[PATCH] x86_64: i386/x86-64 Add nmi watchdog support for new Intel CPUs
[PATCH] x86_64: Avoid broadcasting NMI IPIs
[PATCH] x86_64: fix apic error on bootup
[PATCH] x86_64: enlarge window for stack growth
[PATCH] x86_64: Minor string functions optimizations
[PATCH] x86_64: Move export symbols to their C functions
[PATCH] x86_64: Standardize i386/x86_64 handling of NMI_VECTOR
[PATCH] x86_64: Fix modular pc speaker
[PATCH] x86_64: remove sys32_ni_syscall()
[PATCH] x86_64: Do not use -ffunction-sections for modules
[PATCH] x86_64: Add cpu_relax to apic_wait_icr_idle
[PATCH] x86_64: adjust kstack_depth_to_print default
[PATCH] i386/x86-64: adjust /proc/interrupts column headings
[PATCH] x86_64: Fix race in cpu_local_* on preemptible kernels
[PATCH] x86_64: Fix fast check in safe_smp_processor_id
[PATCH] x86_64: x86_64 setup.c - printing cmp related boottime information
[PATCH] i386/x86-64/ia64: Move polling flag into thread_info_status
...
Manual resolve of trivial conflict in arch/i386/kernel/Makefile
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During some profiling I noticed that default_idle causes a lot of
memory traffic. I think that is caused by the atomic operations
to clear/set the polling flag in thread_info. There is actually
no reason to make this atomic - only the idle thread does it
to itself, other CPUs only read it. So I moved it into ti->status.
Converted i386/x86-64/ia64 for now because that was the easiest
way to fix ACPI which also manipulates these flags in its idle
function.
Cc: Nick Piggin <npiggin@novell.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Len Brown <len.brown@intel.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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As part of the i386 conversion to the generic timekeeping infrastructure, this
introduces a new tsc.c file. The code in this file replaces the TSC
initialization, management and access code currently in timer_tsc.c (which
will be removed) that we want to preserve.
The code also introduces the following functionality:
o tsc_khz: like cpu_khz but stores the TSC frequency on systems that do not
change TSC frequency w/ CPU frequency
o check/mark_tsc_unstable: accessor/modifier flag for TSC timekeeping
usability
o minor cleanups to calibration math.
This patch also includes a one line __cpuinitdata fix from Zwane Mwaikambo.
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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friends
make pm_idle_save, nocst and bm_history __read_mostly
remove initializer from static 'first_run'.
Signed-off-by: Andreas Mohr <andi@lisas.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Len Brown <len.brown@intel.com>
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Broken earlier by me by a x86-64 patch.
The code was optimized away, but the compiler still complained about an
undeclared function.
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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attached patch is 2 more cases i found via running the reference_init.pl
script. These were easy to spot just knowing the file names. There is
one another about init/main.c that i cant exactly zero in. (partly
because i dont know how to interpret the data thats spewed out of the tool).
Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Bug in apic timer removal on C3 patch. We should switch to IPI from APIC timer
only when C3 state is valid.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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branches into release
Signed-off-by: Len Brown <len.brown@intel.com>
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Whenever we see that a CPU is capable of C3 (during ACPI cstate init), we
disable local APIC timer and switch to using a broadcast from external timer
interrupt (IRQ 0). This is needed because Intel CPUs stop the local
APIC timer in C3. This is currently only enabled for Intel CPUs.
Patch below adds the code for i386 and also the ACPI hunk.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This adds all known BIOS versions of IBM R40e Laptops to the C2/C3
processor state blacklist and thus prevents them from crashing.
workaround for http://bugzilla.kernel.org/show_bug.cgi?id=3549
Signed-off-by: Thomas Rosner <kernel-bugs@digital-trauma.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Len Brown <len.brown@intel.com>
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http://bugzilla.kernel.org/show_bug.cgi?id=5165
Change polarity of test for PLVL2_UP flag.
Skip promotion/demotion code when not needed.
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
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Silly bug crept in with the C2/C3 TIF_POLLING_NRFLAG fixes.
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Commit 64c7c8f88559624abdbe12b5da6502e8879f8d28 broke the ACPI C2 and C3
sleep states, because it left TIF_POLLING_NRFLAG active even though
those states do not actually poll the reschedule flag at all. As a
result, the CPU wouldn't get sent an IPI when it was to be woken up, and
would only notice that it had runnable processes on the next timer tick.
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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The ASUS M6Ne specifies C2, implying C1
but not explicitly specifying it.
http://bugzilla.kernel.org/show_bug.cgi?id=4485
Signed-off-by: Janosch Machowinski <jmachowinski@gmx.de>
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
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Linux invokes the AML _PDC method (Processor Driver Capabilities)
to tell the BIOS what features it can handle. While the ACPI
spec says nothing about the OS invoking _PDC multiple times,
doing so with changing bits seems to hopelessly confuse the BIOS
on multiple platforms up to and including crashing the system.
Factor out the _PDC invocation so Linux invokes it only once.
http://bugzilla.kernel.org/show_bug.cgi?id=5483
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
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which tells us if C2 is valid for UP-only, or SMP.
As there is no separate bit for C3, use P_LVL2_UP
bit to cover both C2 and C3.
http://bugzilla.kernel.org/show_bug.cgi?id=5165
Signed-off-by: Venkatesh Pallipadi<venkatesh.pallipadi@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
(cherry picked from 28b86b368af3944eb383078fc5797caf2dc8ce44 commit)
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Note: This ACPI standard compliance may cause regression
on some system, if they have _CST present, but _CST value
is bogus. "nocst" module parameter should workaround
that regression.
http://bugzilla.kernel.org/show_bug.cgi?id=5165
Signed-off-by: Venkatesh Pallipadi<venkatesh.pallipadi@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
(cherry picked from 883baf7f7e81cca26f4683ae0d25ba48f094cc08 commit)
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Properly clear the memory, and set "pr->flags.power" only if a C2 or
deeper state is valid (to make the code match both the comment and
previous behaviour).
This fixes a boot-time lockup reported by Maneesh Soni when using
"maxcpus=1".
Acked-by: Maneesh Soni <maneesh@in.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Make some changes to the NEED_RESCHED and POLLING_NRFLAG to reduce
confusion, and make their semantics rigid. Improves efficiency of
resched_task and some cpu_idle routines.
* In resched_task:
- TIF_NEED_RESCHED is only cleared with the task's runqueue lock held,
and as we hold it during resched_task, then there is no need for an
atomic test and set there. The only other time this should be set is
when the task's quantum expires, in the timer interrupt - this is
protected against because the rq lock is irq-safe.
- If TIF_NEED_RESCHED is set, then we don't need to do anything. It
won't get unset until the task get's schedule()d off.
- If we are running on the same CPU as the task we resched, then set
TIF_NEED_RESCHED and no further action is required.
- If we are running on another CPU, and TIF_POLLING_NRFLAG is *not* set
after TIF_NEED_RESCHED has been set, then we need to send an IPI.
Using these rules, we are able to remove the test and set operation in
resched_task, and make clear the previously vague semantics of
POLLING_NRFLAG.
* In idle routines:
- Enter cpu_idle with preempt disabled. When the need_resched() condition
becomes true, explicitly call schedule(). This makes things a bit clearer
(IMO), but haven't updated all architectures yet.
- Many do a test and clear of TIF_NEED_RESCHED for some reason. According
to the resched_task rules, this isn't needed (and actually breaks the
assumption that TIF_NEED_RESCHED is only cleared with the runqueue lock
held). So remove that. Generally one less locked memory op when switching
to the idle thread.
- Many idle routines clear TIF_POLLING_NRFLAG, and only set it in the inner
most polling idle loops. The above resched_task semantics allow it to be
set until before the last time need_resched() is checked before going into
a halt requiring interrupt wakeup.
Many idle routines simply never enter such a halt, and so POLLING_NRFLAG
can be always left set, completely eliminating resched IPIs when rescheduling
the idle task.
POLLING_NRFLAG width can be increased, to reduce the chance of resched IPIs.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Con Kolivas <kernel@kolivas.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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I recently picked up my older work to remove unnecessary #includes of
sched.h, starting from a patch by Dave Jones to not include sched.h
from module.h. This reduces the number of indirect includes of sched.h
by ~300. Another ~400 pointless direct includes can be removed after
this disentangling (patch to follow later).
However, quite a few indirect includes need to be fixed up for this.
In order to feed the patches through -mm with as little disturbance as
possible, I've split out the fixes I accumulated up to now (complete for
i386 and x86_64, more archs to follow later) and post them before the real
patch. This way this large part of the patch is kept simple with only
adding #includes, and all hunks are independent of each other. So if any
hunk rejects or gets in the way of other patches, just drop it. My scripts
will pick it up again in the next round.
Signed-off-by: Tim Schmielau <tim@physik3.uni-rostock.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Signed-off-by: Len Brown <len.brown@intel.com>
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