linux.git/arch/powerpc/kernel/time.c, branch v3.17

clocksource: Get rid of cycle_last

2014-07-23T22:01:52+00:00

cycle_last was added to the clocksource to support the TSC
validation. We moved that to the core code, so we can get rid of the
extra copy.

Signed-off-by: Thomas Gleixner 
Signed-off-by: John Stultz

powerpc: fix typo 'CONFIG_PMAC'

2014-06-11T07:04:29+00:00

Commit b0d278b7d3ae ("powerpc/perf_event: Reduce latency of calling
perf_event_do_pending") added a check for CONFIG_PMAC were a check for
CONFIG_PPC_PMAC was clearly intended.

Fixes: b0d278b7d3ae ("powerpc/perf_event: Reduce latency of calling perf_event_do_pending")
Signed-off-by: Paul Bolle 
Signed-off-by: Benjamin Herrenschmidt

powerpc: irq work racing with timer interrupt can result in timer interrupt hang

2014-05-12T04:29:28+00:00

I am seeing an issue where a CPU running perf eventually hangs.
Traces show timer interrupts happening every 4 seconds even
when a userspace task is running on the CPU. /proc/timer_list
also shows pending hrtimers have not run in over an hour,
including the scheduler.

Looking closer, decrementers_next_tb is getting set to
0xffffffffffffffff, and at that point we will never take
a timer interrupt again.

In __timer_interrupt() we set decrementers_next_tb to
0xffffffffffffffff and rely on ->event_handler to update it:

        *next_tb = ~(u64)0;
        if (evt->event_handler)
                evt->event_handler(evt);

In this case ->event_handler is hrtimer_interrupt. This will eventually
call back through the clockevents code with the next event to be
programmed:

static int decrementer_set_next_event(unsigned long evt,
                                      struct clock_event_device *dev)
{
        /* Don't adjust the decrementer if some irq work is pending */
        if (test_irq_work_pending())
                return 0;
        __get_cpu_var(decrementers_next_tb) = get_tb_or_rtc() + evt;

If irq work came in between these two points, we will return
before updating decrementers_next_tb and we never process a timer
interrupt again.

This looks to have been introduced by 0215f7d8c53f (powerpc: Fix races
with irq_work). Fix it by removing the early exit and relying on
code later on in the function to force an early decrementer:

       /* We may have raced with new irq work */
       if (test_irq_work_pending())
               set_dec(1);

Signed-off-by: Anton Blanchard 
Cc: stable@vger.kernel.org # 3.14+
Signed-off-by: Benjamin Herrenschmidt

cpuidle/powernv: Add "Fast-Sleep" CPU idle state

2014-03-05T04:57:04+00:00

Fast sleep is one of the deep idle states on Power8 in which local timers of
CPUs stop. On PowerPC we do not have an external clock device which can
handle wakeup of such CPUs. Now that we have the support in the tick broadcast
framework for archs that do not sport such a device and the low level support
for fast sleep, enable it in the cpuidle framework on PowerNV.

Signed-off-by: Preeti U Murthy 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Split timer_interrupt() into timer handling and interrupt handling routines

2014-03-05T04:56:16+00:00

Split timer_interrupt(), which is the local timer interrupt handler on ppc
into routines called during regular interrupt handling and __timer_interrupt(),
which takes care of running local timers and collecting time related stats.

This will enable callers interested only in running expired local timers to
directly call into __timer_interupt(). One of the use cases of this is the
tick broadcast IPI handling in which the sleeping CPUs need to handle the local
timers that have expired.

Signed-off-by: Preeti U Murthy 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Implement tick broadcast IPI as a fixed IPI message

2014-03-05T04:55:04+00:00

For scalability and performance reasons, we want the tick broadcast IPIs
to be handled as efficiently as possible. Fixed IPI messages
are one of the most efficient mechanisms available - they are faster than
the smp_call_function mechanism because the IPI handlers are fixed and hence
they don't involve costly operations such as adding IPI handlers to the target
CPU's function queue, acquiring locks for synchronization etc.

Luckily we have an unused IPI message slot, so use that to implement
tick broadcast IPIs efficiently.

Signed-off-by: Srivatsa S. Bhat 
[Functions renamed to tick_broadcast* and Changelog modified by
 Preeti U. Murthy]
Signed-off-by: Preeti U. Murthy 
Acked-by: Geoff Levand  [For the PS3 part]
Signed-off-by: Benjamin Herrenschmidt

powerpc: Fix races with irq_work

2014-01-15T02:59:03+00:00

If we set irq_work on a processor and immediately afterward, before the
irq work has a chance to be processed, we change the decrementer value,
we can seriously delay the handling of that irq_work.

Fix it by checking in a few places for pending irq work, first before
changing the decrementer in decrementer_set_next_event() and after
changing it in the same function and in timer_interrupt().

Signed-off-by: Benjamin Herrenschmidt

powerpc: Make irq_stat.timers_irqs counting more specific

2013-12-02T03:14:50+00:00

Current irq_stat.timers_irqs counting doesn't discriminate timer event handler
and other timer interrupt(like arch_irq_work_raise). Sometimes we need to know
exactly how much interrupts timer event handler fired, so let's be more specific
on this.

Signed-off-by: Fan Du 
Signed-off-by: Benjamin Herrenschmidt

powerpc/pseries: Duplicate dtl entries sometimes sent to userspace

2013-11-20T23:33:39+00:00

When reading from the dispatch trace log (dtl) userspace interface, I
sometimes see duplicate entries. One example:

# hexdump -C dtl.out

00000000  07 04 00 0c 00 00 48 44  00 00 00 00 00 00 00 00
00000010  00 0c a0 b4 16 83 6d 68  00 00 00 00 00 00 00 00
00000020  00 00 00 00 10 00 13 50  80 00 00 00 00 00 d0 32

00000030  07 04 00 0c 00 00 48 44  00 00 00 00 00 00 00 00
00000040  00 0c a0 b4 16 83 6d 68  00 00 00 00 00 00 00 00
00000050  00 00 00 00 10 00 13 50  80 00 00 00 00 00 d0 32

The problem is in scan_dispatch_log() where we call dtl_consumer()
but bail out before incrementing the index.

To fix this I moved dtl_consumer() after the timebase comparison.

Signed-off-by: Anton Blanchard 
Cc: stable@vger.kernel.org
Signed-off-by: Benjamin Herrenschmidt

Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc

2013-09-06T17:49:42+00:00

Pull powerpc updates from Ben Herrenschmidt:
 "Here's the powerpc batch for this merge window.  Some of the
  highlights are:

   - A bunch of endian fixes ! We don't have full LE support yet in that
     release but this contains a lot of fixes all over arch/powerpc to
     use the proper accessors, call the firmware with the right endian
     mode, etc...

   - A few updates to our "powernv" platform (non-virtualized, the one
     to run KVM on), among other, support for bridging the P8 LPC bus
     for UARTs, support and some EEH fixes.

   - Some mpc51xx clock API cleanups in preparation for a clock API
     overhaul

   - A pile of cleanups of our old math emulation code, including better
     support for using it to emulate optional FP instructions on
     embedded chips that otherwise have a HW FPU.

   - Some infrastructure in selftest, for powerpc now, but could be
     generalized, initially used by some tests for our perf instruction
     counting code.

   - A pile of fixes for hotplug on pseries (that was seriously
     bitrotting)

   - The usual slew of freescale embedded updates, new boards, 64-bit
     hiberation support, e6500 core PMU support, etc..."

* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc: (146 commits)
  powerpc: Correct FSCR bit definitions
  powerpc/xmon: Fix printing of set of CPUs in xmon
  powerpc/pseries: Move lparcfg.c to platforms/pseries
  powerpc/powernv: Return secondary CPUs to firmware on kexec
  powerpc/btext: Fix CONFIG_PPC_EARLY_DEBUG_BOOTX on ppc32
  powerpc: Cleanup handling of the DSCR bit in the FSCR register
  powerpc/pseries: Child nodes are not detached by dlpar_detach_node
  powerpc/pseries: Add mising of_node_put in delete_dt_node
  powerpc/pseries: Make dlpar_configure_connector parent node aware
  powerpc/pseries: Do all node initialization in dlpar_parse_cc_node
  powerpc/pseries: Fix parsing of initial node path in update_dt_node
  powerpc/pseries: Pack update_props_workarea to map correctly to rtas buffer header
  powerpc/pseries: Fix over writing of rtas return code in update_dt_node
  powerpc/pseries: Fix creation of loop in device node property list
  powerpc: Skip emulating & leave interrupts off for kernel program checks
  powerpc: Add more exception trampolines for hypervisor exceptions
  powerpc: Fix location and rename exception trampolines
  powerpc: Add more trap names to xmon
  powerpc/pseries: Add a warning in the case of cross-cpu VPA registration
  powerpc: Update the 00-Index in Documentation/powerpc
  ...