linux.git/kernel/sched/cpudeadline.c, branch v4.16

sched/deadline: Change return value of cpudl_find()

2017-08-10T10:18:17+00:00

cpudl_find() users are only interested in knowing if suitable CPU(s)
were found or not (and then they look at later_mask to know which).

Change cpudl_find() return type accordingly. Aligns with rt code.

Signed-off-by: Byungchul Park 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: 
Cc: 
Cc: 
Cc: 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/1495504859-10960-3-git-send-email-byungchul.park@lge.com
Signed-off-by: Ingo Molnar

sched/deadline: Don't re-initialize 'struct cpudl'

2017-08-10T10:18:13+00:00

The 'struct cpudl' passed to cpudl_init() is already initialized to zero.
Don't do that again.

Signed-off-by: Viresh Kumar 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Vincent Guittot 
Cc: linaro-kernel@lists.linaro.org
Link: http://lkml.kernel.org/r/bd4c229806bc96694b15546207afcc221387d2f5.1492065513.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar

sched/core: Remove the tsk_cpus_allowed() wrapper

2017-03-02T07:42:24+00:00

So the original intention of tsk_cpus_allowed() was to 'future-proof'
the field - but it's pretty ineffectual at that, because half of
the code uses ->cpus_allowed directly ...

Also, the wrapper makes the code longer than the original expression!

So just get rid of it. This also shrinks  a bit.

Acked-by: Linus Torvalds 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar

sched/deadline: Split cpudl_set() into cpudl_set() and cpudl_clear()

2016-09-05T11:29:43+00:00

These 2 exercise independent code paths and need different arguments.

After this change, you call:

  cpudl_clear(cp, cpu);
  cpudl_set(cp, cpu, dl);

instead of:

  cpudl_set(cp, cpu, 0 /* dl */, 0 /* is_valid */);
  cpudl_set(cp, cpu, dl, 1 /* is_valid */);

Signed-off-by: Tommaso Cucinotta 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Luca Abeni 
Reviewed-by: Juri Lelli 
Cc: Juri Lelli 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-dl@retis.sssup.it
Link: http://lkml.kernel.org/r/1471184828-12644-4-git-send-email-tommaso.cucinotta@sssup.it
Signed-off-by: Ingo Molnar

sched/deadline: Make CPU heap faster avoiding real swaps on heapify

2016-09-05T11:29:43+00:00

This change goes from heapify() ops done by swapping with parent/child
so that the item to fix moves along, to heapify() ops done by just
pulling the parent/child chain by 1 pos, then storing the item to fix
just at the end. On a non-trivial heapify(), this performs roughly half
stores wrt swaps.

This has been measured to achieve up to 10% of speed-up for cpudl_set()
calls, with a randomly generated workload of 1K,10K,100K random heap
insertions and deletions (75% cpudl_set() calls with is_valid=1 and
25% with is_valid=0), and randomly generated cpu IDs, with up to 256
CPUs, as measured on an Intel Core2 Duo.

Signed-off-by: Tommaso Cucinotta 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Luca Abeni 
Reviewed-by: Juri Lelli 
Cc: Juri Lelli 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-dl@retis.sssup.it
Link: http://lkml.kernel.org/r/1471184828-12644-3-git-send-email-tommaso.cucinotta@sssup.it
Signed-off-by: Ingo Molnar

sched/deadline: Refactor CPU heap code

2016-09-05T11:29:42+00:00

 1. heapify up factored out in new dedicated function heapify_up()
    (avoids repetition of same code)

 2. call to cpudl_change_key() replaced with heapify_up() when
    cpudl_set actually inserts a new node in the heap

 3. cpudl_change_key() replaced with heapify() that heapifies up
    or down as needed.

Signed-off-by: Tommaso Cucinotta 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Luca Abeni 
Reviewed-by: Juri Lelli 
Cc: Juri Lelli 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-dl@retis.sssup.it
Link: http://lkml.kernel.org/r/1471184828-12644-2-git-send-email-tommaso.cucinotta@sssup.it
Signed-off-by: Ingo Molnar

sched/deadline: Fix wrap-around in DL heap

2016-08-10T11:32:55+00:00

Current code in cpudeadline.c has a bug in re-heapifying when adding a
new element at the end of the heap, because a deadline value of 0 is
temporarily set in the new elem, then cpudl_change_key() is called
with the actual elem deadline as param.

However, the function compares the new deadline to set with the one
previously in the elem, which is 0.  So, if current absolute deadlines
grew so much to have negative values as s64, the comparison in
cpudl_change_key() makes the wrong decision.  Instead, as from
dl_time_before(), the kernel should handle correctly abs deadlines
wrap-arounds.

This patch fixes the problem with a minimally invasive change that
forces cpudl_change_key() to heapify up in this case.

Signed-off-by: Tommaso Cucinotta 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Luca Abeni 
Cc: Juri Lelli 
Cc: Juri Lelli 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/1468921493-10054-2-git-send-email-tommaso.cucinotta@sssup.it
Signed-off-by: Ingo Molnar

sched/core: Use tsk_cpus_allowed() instead of accessing ->cpus_allowed

2016-05-12T07:55:35+00:00

Use the future-safe accessor for struct task_struct's.

Signed-off-by: Thomas Gleixner 
Signed-off-by: Sebastian Andrzej Siewior 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Linus Torvalds 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/1462969411-17735-1-git-send-email-bigeasy@linutronix.de
Signed-off-by: Ingo Molnar

sched/deadline: Unify dl_time_before() usage

2015-09-23T07:51:25+00:00

Move dl_time_before() static definition in include/linux/sched/deadline.h
so that it can be used by different parties without being re-defined.

Reported-by: Luca Abeni 
Signed-off-by: Juri Lelli 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Linus Torvalds 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/1441188096-23021-3-git-send-email-juri.lelli@arm.com
Signed-off-by: Ingo Molnar

sched/deadline: Remove cpu_active_mask from cpudl_find()

2015-02-04T06:52:29+00:00

cpu_active_mask is rarely changed (only on hotplug), so remove this
operation to gain a little performance.

If there is a change in cpu_active_mask, rq_online_dl() and
rq_offline_dl() should take care of it normally, so cpudl::free_cpus
carries enough information for us.

For the rare case when a task is put onto a dying cpu (which
rq_offline_dl() can't handle in a timely fashion), it will be
handled through _cpu_down()->...->multi_cpu_stop()->migration_call()
->migrate_tasks(), preventing the task from hanging on the
dead cpu.

Cc: Juri Lelli 
Signed-off-by: Xunlei Pang 
[peterz: changelog]
Signed-off-by: Peter Zijlstra (Intel) 
Link: http://lkml.kernel.org/r/1421642980-10045-2-git-send-email-pang.xunlei@linaro.org
Cc: Linus Torvalds 
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar