From 35664fd41e1c8cc4f0b89f6a51db5af39ba50640 Mon Sep 17 00:00:00 2001 From: Rik van Riel Date: Mon, 27 Jan 2014 17:03:46 -0500 Subject: [PATCH] sched/numa: Do statistics calculation using local variables only The current code in task_numa_placement calculates the difference between the old and the new value, but also temporarily stores half of the old value in the per-process variables. The NUMA balancing code looks at those per-process variables, and having other tasks temporarily see halved statistics could lead to unwanted numa migrations. This can be avoided by doing all the math in local variables. This change also simplifies the code a little. Signed-off-by: Rik van Riel Acked-by: Mel Gorman Signed-off-by: Peter Zijlstra Cc: Chegu Vinod Link: http://lkml.kernel.org/r/1390860228-21539-8-git-send-email-riel@redhat.com Signed-off-by: Ingo Molnar --- kernel/sched/fair.c | 12 ++++-------- 1 file changed, 4 insertions(+), 8 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 8fc3a8234817..4c449907a10e 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1513,12 +1513,9 @@ static void task_numa_placement(struct task_struct *p) long diff, f_diff, f_weight; i = task_faults_idx(nid, priv); - diff = -p->numa_faults_memory[i]; - f_diff = -p->numa_faults_cpu[i]; /* Decay existing window, copy faults since last scan */ - p->numa_faults_memory[i] >>= 1; - p->numa_faults_memory[i] += p->numa_faults_buffer_memory[i]; + diff = p->numa_faults_buffer_memory[i] - p->numa_faults_memory[i] / 2; fault_types[priv] += p->numa_faults_buffer_memory[i]; p->numa_faults_buffer_memory[i] = 0; @@ -1532,13 +1529,12 @@ static void task_numa_placement(struct task_struct *p) f_weight = div64_u64(runtime << 16, period + 1); f_weight = (f_weight * p->numa_faults_buffer_cpu[i]) / (total_faults + 1); - p->numa_faults_cpu[i] >>= 1; - p->numa_faults_cpu[i] += f_weight; + f_diff = f_weight - p->numa_faults_cpu[i] / 2; p->numa_faults_buffer_cpu[i] = 0; + p->numa_faults_memory[i] += diff; + p->numa_faults_cpu[i] += f_diff; faults += p->numa_faults_memory[i]; - diff += p->numa_faults_memory[i]; - f_diff += p->numa_faults_cpu[i]; p->total_numa_faults += diff; if (p->numa_group) { /* safe because we can only change our own group */