linux-toradex.git/include/linux/cpumask.h, branch v5.8-rc3

sched/core: Distribute tasks within affinity masks

2020-03-20T12:06:18+00:00

Currently, when updating the affinity of tasks via either cpusets.cpus,
or, sched_setaffinity(); tasks not currently running within the newly
specified mask will be arbitrarily assigned to the first CPU within the
mask.

This (particularly in the case that we are restricting masks) can
result in many tasks being assigned to the first CPUs of their new
masks.

This:
 1) Can induce scheduling delays while the load-balancer has a chance to
    spread them between their new CPUs.
 2) Can antogonize a poor load-balancer behavior where it has a
    difficult time recognizing that a cross-socket imbalance has been
    forced by an affinity mask.

This change adds a new cpumask interface to allow iterated calls to
distribute within the intersection of the provided masks.

The cases that this mainly affects are:
 - modifying cpuset.cpus
 - when tasks join a cpuset
 - when modifying a task's affinity via sched_setaffinity(2)

Signed-off-by: Paul Turner 
Signed-off-by: Josh Don 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Qais Yousef 
Tested-by: Qais Yousef 
Link: https://lkml.kernel.org/r/20200311010113.136465-1-joshdon@google.com

include/linux/cpumask.h: don't calculate length of the input string

2020-02-04T03:05:27+00:00

New design of inner bitmap_parse() allows to avoid calculating the size of
a null-terminated string.

Link: http://lkml.kernel.org/r/20200102043031.30357-8-yury.norov@gmail.com
Signed-off-by: Yury Norov 
Reviewed-by: Andy Shevchenko 
Cc: Amritha Nambiar 
Cc: Arnaldo Carvalho de Melo 
Cc: Chris Wilson 
Cc: Kees Cook 
Cc: Matthew Wilcox 
Cc: Miklos Szeredi 
Cc: Rasmus Villemoes 
Cc: Steffen Klassert 
Cc: "Tobin C . Harding" 
Cc: Vineet Gupta 
Cc: Will Deacon 
Cc: Willem de Bruijn 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cpumask: nicer for_each_cpumask_and() signature

2019-09-26T00:51:40+00:00

Mask arguments can be swapped without changing anything.  Make arguments
names reflect that:

	#define for_each_cpu_and(cpu, mask1, mask2)

Link: http://lkml.kernel.org/r/20190724183350.GA15041@avx2
Signed-off-by: Alexey Dobriyan 
Reviewed-by: Andrew Morton 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cpu/hotplug: Cache number of online CPUs

2019-07-25T13:48:01+00:00

Re-evaluating the bitmap wheight of the online cpus bitmap in every
invocation of num_online_cpus() over and over is a pretty useless
exercise. Especially when num_online_cpus() is used in code paths
like the IPI delivery of x86 or the membarrier code.

Cache the number of online CPUs in the core and just return the cached
variable. The accessor function provides only a snapshot when used without
protection against concurrent CPU hotplug.

The storage needs to use an atomic_t because the kexec and reboot code
(ab)use set_cpu_online() in their 'shutdown' handlers without any form of
serialization as pointed out by Mathieu. Regular CPU hotplug usage is
properly serialized.

Signed-off-by: Thomas Gleixner 
Reviewed-by: Mathieu Desnoyers 
Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1907091622590.1634@nanos.tec.linutronix.de

cpumask: Implement cpumask_or_equal()

2019-07-25T13:47:37+00:00

The IPI code of x86 needs to evaluate whether the target cpumask is equal
to the cpu_online_mask or equal except for the calling CPU.

To replace the current implementation which requires the usage of a
temporary cpumask, which might involve allocations, add a new function
which compares a cpumask to the result of two other cpumasks which are
or'ed together before comparison.

This allows to make the required decision in one go and the calling code
then can check for the calling CPU being set in the target mask with
cpumask_test_cpu().

Signed-off-by: Thomas Gleixner 
Acked-by: Peter Zijlstra (Intel) 
Link: https://lkml.kernel.org/r/20190722105220.585449120@linutronix.de

smp/hotplug: Track booted once CPUs in a cpumask

2019-07-25T13:47:37+00:00

The booted once information which is required to deal with the MCE
broadcast issue on X86 correctly is stored in the per cpu hotplug state,
which is perfectly fine for the intended purpose.

X86 needs that information for supporting NMI broadcasting via shortcuts,
but retrieving it from per cpu data is cumbersome.

Move it to a cpumask so the information can be checked against the
cpu_present_mask quickly.

No functional change intended.

Signed-off-by: Thomas Gleixner 
Acked-by: Peter Zijlstra (Intel) 
Link: https://lkml.kernel.org/r/20190722105219.818822855@linutronix.de

include/linux/cpumask.h: fix double string traverse in cpumask_parse

2019-05-15T02:52:50+00:00

cpumask_parse() finds first occurrence of either or strchr() and
strlen().  We can do it better with a single call of strchrnul().

[akpm@linux-foundation.org: remove unneeded cast]
Link: http://lkml.kernel.org/r/20190409204208.12190-1-ynorov@marvell.com
Signed-off-by: Yury Norov 
Acked-by: Rasmus Villemoes 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cpumask: make cpumask_next_wrap available without smp

2018-08-13T16:05:05+00:00

The kbuild robot shows build failure on machines without CONFIG_SMP:

  drivers/net/virtio_net.c:1916:10: error:
    implicit declaration of function 'cpumask_next_wrap'

cpumask_next_wrap is exported from lib/cpumask.o, which has

    lib-$(CONFIG_SMP) += cpumask.o

same as other functions, also define it as static inline in the
NR_CPUS==1 branch in include/linux/cpumask.h.

If wrap is true and next == start, return nr_cpumask_bits, or 1.
Else wrap across the range of valid cpus, here [0].

Fixes: 2ca653d607ce ("virtio_net: Stripe queue affinities across cores.")
Signed-off-by: Willem de Bruijn 
Tested-by: Krzysztof Kozlowski 
Signed-off-by: David S. Miller

net: Refactor XPS for CPUs and Rx queues

2018-07-02T00:06:23+00:00

Refactor XPS code to support Tx queue selection based on
CPU(s) map or Rx queue(s) map.

Signed-off-by: Amritha Nambiar 
Signed-off-by: David S. Miller

cpumask: Make for_each_cpu_wrap() available on UP as well

2018-02-16T09:40:24+00:00

for_each_cpu_wrap() was originally added in the #else half of a
large "#if NR_CPUS == 1" statement, but was omitted in the #if
half.  This patch adds the missing #if half to prevent compile
errors when NR_CPUS is 1.

Reported-by: kbuild test robot 
Signed-off-by: Michael Kelley 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: kys@microsoft.com
Cc: martin.petersen@oracle.com
Cc: mikelley@microsoft.com
Fixes: c743f0a5c50f ("sched/fair, cpumask: Export for_each_cpu_wrap()")
Link: http://lkml.kernel.org/r/SN6PR1901MB2045F087F59450507D4FCC17CBF50@SN6PR1901MB2045.namprd19.prod.outlook.com
Signed-off-by: Ingo Molnar