sched: Refactor task_struct to use numa_faults instead of numa_* pointers

This patch simplifies task_struct by removing the four numa_* pointers
in the same array and replacing them with the array pointer. By doing this,
on x86_64, the size of task_struct is reduced by 3 ulong pointers (24 bytes on
x86_64).

A new parameter is added to the task_faults_idx function so that it can return
an index to the correct offset, corresponding with the old precalculated
pointers.

All of the code in sched/ that depended on task_faults_idx and numa_* was
changed in order to match the new logic.

Signed-off-by: Iulia Manda <iulia.manda21@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: mgorman@suse.de
Cc: dave@stgolabs.net
Cc: riel@redhat.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20141031001331.GA30662@winterfell
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 1 insertions, 2 deletions

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index df0569ebec0f..72d9d926a034 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1857,8 +1857,7 @@ static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
         p->numa_scan_seq = p->mm ? p->mm->numa_scan_seq : 0;
         p->numa_scan_period = sysctl_numa_balancing_scan_delay;
         p->numa_work.next = &p->numa_work;
-        p->numa_faults_memory = NULL;
-        p->numa_faults_buffer_memory = NULL;
+        p->numa_faults = NULL;
         p->last_task_numa_placement = 0;
         p->last_sum_exec_runtime = 0;