linux-stable.git/kernel/sched/cpudeadline.c, branch linux-4.2.y

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

sched/deadline: Modify cpudl::free_cpus to reflect rd->online

2015-01-30T18:39:16+00:00

Currently, cpudl::free_cpus contains all CPUs during init, see
cpudl_init(). When calling cpudl_find(), we have to add rd->span
to avoid selecting the cpu outside the current root domain, because
cpus_allowed cannot be depended on when performing clustered
scheduling using the cpuset, see find_later_rq().

This patch adds cpudl_set_freecpu() and cpudl_clear_freecpu() for
changing cpudl::free_cpus when doing rq_online_dl()/rq_offline_dl(),
so we can avoid the rd->span operation when calling cpudl_find()
in find_later_rq().

Signed-off-by: Xunlei Pang 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Juri Lelli 
Cc: Linus Torvalds 
Link: http://lkml.kernel.org/r/1421642980-10045-1-git-send-email-pang.xunlei@linaro.org
Signed-off-by: Ingo Molnar

sched/deadline: Fix inter- exclusive cpusets migrations

2014-09-24T12:46:57+00:00

Users can perform clustered scheduling using the cpuset facility.
After an exclusive cpuset is created, task migrations happen only
between CPUs belonging to the same cpuset. Inter- cpuset migrations
can only happen when the user requires so, moving a task between
different cpusets. This behaviour is broken in SCHED_DEADLINE, as
currently spurious inter- cpuset migration may happen without user
intervention.

This patch fix the problem (and shuffles the code a bit to improve
clarity).

Signed-off-by: Juri Lelli 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: raistlin@linux.it
Cc: michael@amarulasolutions.com
Cc: fchecconi@gmail.com
Cc: daniel.wagner@bmw-carit.de
Cc: vincent@legout.info
Cc: luca.abeni@unitn.it
Cc: Linus Torvalds 
Link: http://lkml.kernel.org/r/1411118561-26323-4-git-send-email-juri.lelli@arm.com
Signed-off-by: Ingo Molnar

sched/deadline: Replace NR_CPUS arrays

2014-05-22T08:21:28+00:00

Tejun reported that his resume was failing due to order-3 allocations
from sched_domain building.

Replace the NR_CPUS arrays in there with a dynamically allocated
array.

Reported-by: Tejun Heo 
Signed-off-by: Peter Zijlstra 
Acked-by: Juri Lelli 
Cc: Johannes Weiner 
Cc: Linus Torvalds 
Link: http://lkml.kernel.org/n/tip-kat4gl1m5a6dwy6nzuqox45e@git.kernel.org
Signed-off-by: Ingo Molnar

sched/deadline: Fix memory leak

2014-05-07T09:51:32+00:00

Free cpudl->free_cpus allocated in cpudl_init().

Signed-off-by: Li Zefan 
Acked-by: Juri Lelli 
Signed-off-by: Peter Zijlstra 
Cc:  # 3.14+
Link: http://lkml.kernel.org/r/534F36CE.2000409@huawei.com
Signed-off-by: Ingo Molnar

sched/deadline: Switch CPU's presence test order

2014-02-27T11:29:40+00:00

Commit 82b9580 ("sched/deadline: Test for CPU's presence explicitly")
changed how we check if a CPU returned by cpudeadline machinery is
valid. But, we don't want to call cpu_present() if best_cpu is
equal to -1. So, switch the order of tests inside WARN_ON().

Signed-off-by: Juri Lelli 
Signed-off-by: Peter Zijlstra 
Cc: boris.ostrovsky@oracle.com
Cc: konrad.wilk@oracle.com
Cc: rostedt@goodmis.org
Link: http://lkml.kernel.org/r/1393238832-9100-1-git-send-email-juri.lelli@gmail.com
Signed-off-by: Ingo Molnar

sched/deadline: Test for CPU's presence explicitly

2014-02-21T20:27:10+00:00

A hot-removed CPU may have ID that is numerically larger than the number of
existing CPUs in the system (e.g. we can unplug CPU 4 from a system that
has CPUs 0, 1 and 4).

Thus the WARN_ONs should check whether the CPU in question is currently
present, not whether its ID value is less than num_present_cpus().

Cc: Ingo Molnar 
Cc: Juri Lelli 
Cc: Steven Rostedt 
Reported-by: Konrad Rzeszutek Wilk 
Signed-off-by: Boris Ostrovsky 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1392646353-1874-1-git-send-email-boris.ostrovsky@oracle.com
Signed-off-by: Thomas Gleixner

sched/deadline: Fix sparse static warnings

2014-01-16T08:27:03+00:00

new sparse warnings:

  >> kernel/sched/cpudeadline.c:38:6: sparse: symbol 'cpudl_exchange' was not declared. Should it be static?
  >> kernel/sched/cpudeadline.c:46:6: sparse: symbol 'cpudl_heapify' was not declared. Should it be static?
  >> kernel/sched/cpudeadline.c:71:6: sparse: symbol 'cpudl_change_key' was not declared. Should it be static?
  >> kernel/sched/cpudeadline.c:195:15: sparse: memset with byte count of 163928

Signed-off-by: Fengguang Wu 
Signed-off-by: Peter Zijlstra 
Cc: Juri Lelli 
Fixes: 6bfd6d72f51c ("sched/deadline: speed up SCHED_DEADLINE pushes with a push-heap")
Link: http://lkml.kernel.org/r/52d47f8c.EYJsA5+mELPBk4t6\%fengguang.wu@intel.com
Signed-off-by: Ingo Molnar

sched/deadline: speed up SCHED_DEADLINE pushes with a push-heap

2014-01-13T12:46:46+00:00

Data from tests confirmed that the original active load balancing
logic didn't scale neither in the number of CPU nor in the number of
tasks (as sched_rt does).

Here we provide a global data structure to keep track of deadlines
of the running tasks in the system. The structure is composed by
a bitmask showing the free CPUs and a max-heap, needed when the system
is heavily loaded.

The implementation and concurrent access scheme are kept simple by
design. However, our measurements show that we can compete with sched_rt
on large multi-CPUs machines [1].

Only the push path is addressed, the extension to use this structure
also for pull decisions is straightforward. However, we are currently
evaluating different (in order to decrease/avoid contention) data
structures to solve possibly both problems. We are also going to re-run
tests considering recent changes inside cpupri [2].

 [1] http://retis.sssup.it/~jlelli/papers/Ospert11Lelli.pdf
 [2] http://www.spinics.net/lists/linux-rt-users/msg06778.html

Signed-off-by: Juri Lelli 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1383831828-15501-14-git-send-email-juri.lelli@gmail.com
Signed-off-by: Ingo Molnar