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  1. 11 Sep, 2009 4 commits
    • Paul Mackerras's avatar
      powerpc/perf_counters: Reduce stack usage of power_check_constraints · e51ee31e
      Paul Mackerras authored 
      Michael Ellerman reported stack-frame size warnings being produced
for power_check_constraints(), which uses an 8*8 array of u64 and
two 8*8 arrays of unsigned long, which are currently allocated on the
stack, along with some other smaller variables.  These arrays come
to 1.5kB on 64-bit or 1kB on 32-bit, which is a bit too much for the
stack.

This fixes the problem by putting these arrays in the existing
per-cpu cpu_hw_counters struct.  This is OK because two of the call
sites have interrupts disabled already; for the third call site we
use get_cpu_var, which disables preemption, so we know we won't
get a context switch while we're in power_check_constraints().
Note that power_check_constraints() can be called during context
switch but is not called from interrupts.
Reported-by: default avatarMichael Ellerman <michael@ellerman.id.au>
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
Cc: <stable@kernel.org)
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
      e51ee31e
    • Paul Mackerras's avatar
      powerpc: Fix bug where perf_counters breaks oprofile · a6dbf93a
      Paul Mackerras authored 
      Currently there is a bug where if you use oprofile on a pSeries
machine, then use perf_counters, then use oprofile again, oprofile
will not work correctly; it will lose the PMU configuration the next
time the hypervisor does a partition context switch, and thereafter
won't count anything.

Maynard Johnson identified the sequence causing the problem:
- oprofile setup calls ppc_enable_pmcs(), which calls
  pseries_lpar_enable_pmcs, which tells the hypervisor that we want
  to use the PMU, and sets the "PMU in use" flag in the lppaca.
  This flag tells the hypervisor whether it needs to save and restore
  the PMU config.
- The perf_counter code sets and clears the "PMU in use" flag directly
  as it context-switches the PMU between tasks, and leaves it clear
  when it finishes.
- oprofile setup, called for a new oprofile run, calls ppc_enable_pmcs,
  which does nothing because it has already been called.  In particular
  it doesn't set the "PMU in use" flag.

This fixes the problem by arranging for ppc_enable_pmcs to always set
the "PMU in use" flag.  It makes the perf_counter code call
ppc_enable_pmcs also rather than calling the lower-level function
directly, and removes the setting of the "PMU in use" flag from
pseries_lpar_enable_pmcs, since that is now done in its caller.

This also removes the declaration of pasemi_enable_pmcs because it
isn't defined anywhere.
Reported-by: default avatarMaynard Johnson <mpjohn@us.ibm.com>
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
Cc: <stable@kernel.org)
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
      a6dbf93a
    • Kumar Gala's avatar
      powerpc/85xx: Fix SMP compile error and allow NULL for smp_ops · 757cbd46
      Kumar Gala authored 
      The following commit introduced a compile error since it removed
the implementation of smp_85xx_basic_setup:

commit 77c0a700
Author: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date:   Fri Aug 28 14:25:04 2009 +1000

    powerpc: Properly start decrementer on BookE secondary CPUs

Make it so that smp_ops probe() and setup_cpu() can be set to NULL.
Signed-off-by: default avatarKumar Gala <galak@kernel.crashing.org>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
      757cbd46
    • Wolfram Sang's avatar
      powerpc/irq: Improve nanodoc · 8708d002
      Wolfram Sang authored 
      The OF helpers look like nanodoc but are missing the header. Fix this and a
typo (s/nad/and/) while we are here.
Signed-off-by: default avatarWolfram Sang <w.sang@pengutronix.de>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
      8708d002
  3. 02 Sep, 2009 6 commits
  5. 31 Aug, 2009 6 commits
  7. 28 Aug, 2009 21 commits
  9. 27 Aug, 2009 3 commits
    • Benjamin Herrenschmidt's avatar
      Merge commit 'kumar/next' into next · 3c2ee2d9
      Benjamin Herrenschmidt authored
      3c2ee2d9
    • Gautham R Shenoy's avatar
      powerpc/pseries: Reduce the polling interval in __cpu_up() · 67764263
      Gautham R Shenoy authored 
      Time time taken for a single cpu online operation on a pseries machine
is as follows:
Dedicated LPAR (POWER6): ~220ms.
Shared LPAR (POWER5)   : ~240ms.

Of this time, approximately 200ms is taken up by __cpu_up(). This is because
we poll every 200ms to check if the new cpu has notified it's presence
through the cpu_callin_map. We repeat this operation until the new cpu sets
the value in cpu_callin_map or 5 seconds elapse, whichever comes earlier.

However, using completion_structs instead of polling loops,
the time taken by the new processor to indicate it's presence has
found to be less than 1ms on pseries. This method however may not
work on all powerpc platforms due to the time-base synchronization code.

Keeping this in mind, we could reduce msleep polling interval from
200ms to 1ms while retaining the 5 second timeout.

With this, the time taken for a cpu online operation changes as follows:
Dedicated LPAR (POWER6): 20-25ms.
Shared LPAR (POWER5)   : 60-80ms.

In both these cases, it was found that the code polls through the loop
only once indicating that 1ms is a reasonable value, atleast on pseries.

The code needs testing on other powerpc platforms.
Signed-off-by: default avatarGautham R Shenoy <ego@in.ibm.com>
Acked-by: default avatarJoel Schopp <jschopp@austin.ibm.com>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
      67764263
    • Bastian Blank's avatar
      powerpc: Remove SMP warning from PowerMac cpufreq · 6fdc31a2
      Bastian Blank authored 
      On Thu, Aug 13, 2009 at 04:14:58PM +1000, Benjamin Herrenschmidt wrote:
> On Tue, 2009-08-11 at 11:39 +0200, Bastian Blank wrote:
> > This patch just disables this driver on SMP kernels, as it is obviously
> > not supported.
> Why not remove the #error instead ? :-) I don't think it's still
> meaningful, especially since we use the timebase for delays nowadays
> which doesn't depend on the CPU frequency...

Your call. Take this one:

The build of a PowerMac 32bit kernel currently fails with

error: #warning "WARNING, CPUFREQ not recommended on SMP kernels"

Thie patch removes the not longer applicable SMP warning from the
PowerMac cpufreq code.
Signed-off-by: default avatarBastian Blank <waldi@debian.org>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
      6fdc31a2