linux-toradex.git/include/linux/smp.h, branch v2.6.31.2

remove put_cpu_no_resched()

2009-06-17T02:47:48+00:00

put_cpu_no_resched() is an optimization of put_cpu() which unfortunately
can cause high latencies.

The nfs iostats code uses put_cpu_no_resched() in a code sequence where a
reschedule request caused by an interrupt between the get_cpu() and the
put_cpu_no_resched() can delay the reschedule for at least HZ.

The other users of put_cpu_no_resched() optimize correctly in interrupt
code, but there is no real harm in using the put_cpu() function which is
an alias for preempt_enable().  The extra check of the preemmpt count is
not as critical as the potential source of missing a reschedule.

Debugged in the preempt-rt tree and verified in mainline.

Impact: remove a high latency source

[akpm@linux-foundation.org: build fix]
Signed-off-by: Thomas Gleixner 
Acked-by: Ingo Molnar 
Cc: Tony Luck 
Cc: Trond Myklebust 
Cc: "J. Bruce Fields" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

panic, smp: provide smp_send_stop() wrapper on UP too

2009-03-13T10:24:31+00:00

Impact: cleanup, no code changed

Remove an ugly #ifdef CONFIG_SMP from panic(), by providing
an smp_send_stop() wrapper on UP too.

LKML-Reference: <49B91A7E.76E4.0078.0@novell.com>
Signed-off-by: Ingo Molnar

Merge branch 'x86/core' into core/ipi

2009-03-13T10:05:58+00:00

generic-ipi: remove CSD_FLAG_WAIT

2009-02-25T13:13:44+00:00

Oleg noticed that we don't strictly need CSD_FLAG_WAIT, rework
the code so that we can use CSD_FLAG_LOCK for both purposes.

Signed-off-by: Peter Zijlstra 
Cc: Oleg Nesterov 
Cc: Linus Torvalds 
Cc: Nick Piggin 
Cc: Jens Axboe 
Cc: "Paul E. McKenney" 
Cc: Rusty Russell 
Signed-off-by: Ingo Molnar

smp, generic: introduce arch_disable_smp_support(), build fix

2009-02-05T21:27:57+00:00

This function should be provided on UP too.

Signed-off-by: Ingo Molnar

smp, generic: introduce arch_disable_smp_support() instead of disable_ioapic_setup()

2009-02-05T21:27:54+00:00

Impact: cleanup

disable_ioapic_setup() in init/main.c is ugly as the function is
x86-specific. The #ifdef inline prototype there is ugly too.

Replace it with a generic arch_disable_smp_support() function - which
has a weak alias for non-x86 architectures and for non-ioapic x86 builds.

Signed-off-by: Ingo Molnar

smp_call_function_single(): be slightly less stupid

2009-01-11T02:41:58+00:00

If you do

	smp_call_function_single(expression-with-side-effects, ...)

then expression-with-side-effects never gets evaluated on UP builds.

As always, implementing it in C is the correct thing to do.

While we're there, uninline it for size and possible header dependency
reasons.

And create a new kernel/up.c, as a place in which to put
uniprocessor-specific code and storage.  It should mirror kernel/smp.c.

Signed-off-by: Andrew Morton 
Signed-off-by: Ingo Molnar

cpumask: smp_call_function_many()

2008-12-29T22:35:16+00:00

Impact: Implementation change to remove cpumask_t from stack.

Actually change smp_call_function_mask() to smp_call_function_many().
We avoid cpumasks on the stack in this version.

(S390 has its own version, but that's going away apparently).

We have to do some dancing to figure out if 0 or 1 other cpus are in
the mask supplied and the online mask without allocating a tmp
cpumask.  It's still fairly cheap.

We allocate the cpumask at the end of the call_function_data
structure: if allocation fails we fallback to smp_call_function_single
rather than using the baroque quiescing code (which needs a cpumask on
stack).

(Thanks to Hiroshi Shimamoto for spotting several bugs in previous versions!)

Signed-off-by: Rusty Russell 
Signed-off-by: Mike Travis 
Cc: Hiroshi Shimamoto 
Cc: npiggin@suse.de
Cc: axboe@kernel.dk

Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6

2008-12-29T21:32:35+00:00

cpumask: add sysfs displays for configured and disabled cpu maps

2008-12-19T07:17:04+00:00

Impact: add new sysfs files.

Add sysfs files "kernel_max" and "offline" to display the max CPU index
allowed (NR_CPUS-1), and the map of cpus that are offline.

Cpus can be offlined via HOTPLUG, disabled by the BIOS ACPI tables, or
if they exceed the number of cpus allowed by the NR_CPUS config option,
or the "maxcpus=NUM" kernel start parameter.

The "possible_cpus=NUM" parameter can also extend the number of possible
cpus allowed, in which case the cpus not present at startup will be
in the offline state.  (These cpus can be HOTPLUGGED ON after system
startup [pending a follow-on patch to provide the capability via the
/sys/devices/sys/cpu/cpuN/online mechanism to bring them online.])

By design, the "offlined cpus > possible cpus" display will always
use the following formats:

  * all possible cpus online:   "x$"    or "x-y$"
  * some possible cpus offline: ".*,x$" or ".*,x-y$"

where:
  x == number of possible cpus (nr_cpu_ids); and
  y == number of cpus >= NR_CPUS or maxcpus (if y > x).

One use of this feature is for distros to select (or configure) the
appropriate kernel to install for the resident system.

Notes:
  * cpus offlined <= possible cpus will be printed for all architectures.
  * cpus offlined >  possible cpus will only be printed for arches that
  	set 'total_cpus' [X86 only in this patch].

Based on tip/cpus4096 + .../rusty/linux-2.6-for-ingo.git/master +
	 x86-only-patches sent 12/15.

Signed-off-by: Mike Travis 
Signed-off-by: Rusty Russell