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>
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 4400ddc..bd7c14b 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1597,28 +1597,23 @@
struct numa_group *numa_group;
/*
- * Exponential decaying average of faults on a per-node basis.
- * Scheduling placement decisions are made based on the these counts.
- * The values remain static for the duration of a PTE scan
+ * numa_faults is an array split into four regions:
+ * faults_memory, faults_cpu, faults_memory_buffer, faults_cpu_buffer
+ * in this precise order.
+ *
+ * faults_memory: Exponential decaying average of faults on a per-node
+ * basis. Scheduling placement decisions are made based on these
+ * counts. The values remain static for the duration of a PTE scan.
+ * faults_cpu: Track the nodes the process was running on when a NUMA
+ * hinting fault was incurred.
+ * faults_memory_buffer and faults_cpu_buffer: Record faults per node
+ * during the current scan window. When the scan completes, the counts
+ * in faults_memory and faults_cpu decay and these values are copied.
*/
- unsigned long *numa_faults_memory;
+ unsigned long *numa_faults;
unsigned long total_numa_faults;
/*
- * numa_faults_buffer records faults per node during the current
- * scan window. When the scan completes, the counts in
- * numa_faults_memory decay and these values are copied.
- */
- unsigned long *numa_faults_buffer_memory;
-
- /*
- * Track the nodes the process was running on when a NUMA hinting
- * fault was incurred.
- */
- unsigned long *numa_faults_cpu;
- unsigned long *numa_faults_buffer_cpu;
-
- /*
* numa_faults_locality tracks if faults recorded during the last
* scan window were remote/local. The task scan period is adapted
* based on the locality of the faults with different weights