From 0437e109e1841607f2988891eaa36c531c6aa6ac Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Mon, 9 Jul 2007 18:51:57 +0200 Subject: sched: zap the migration init / cache-hot balancing code the SMP load-balancer uses the boot-time migration-cost estimation code to attempt to improve the quality of balancing. The reason for this code is that the discrete priority queues do not preserve the order of scheduling accurately, so the load-balancer skips tasks that were running on a CPU 'recently'. this code is fundamental fragile: the boot-time migration cost detector doesnt really work on systems that had large L3 caches, it caused boot delays on large systems and the whole cache-hot concept made the balancing code pretty undeterministic as well. (and hey, i wrote most of it, so i can say it out loud that it sucks ;-) under CFS the same purpose of cache affinity can be achieved without any special cache-hot special-case: tasks are sorted in the 'timeline' tree and the SMP balancer picks tasks from the left side of the tree, thus the most cache-cold task is balanced automatically. Signed-off-by: Ingo Molnar --- arch/sparc/kernel/smp.c | 10 ---------- 1 file changed, 10 deletions(-) (limited to 'arch/sparc/kernel') diff --git a/arch/sparc/kernel/smp.c b/arch/sparc/kernel/smp.c index 4d9ad59031b..4fea3ac7bff 100644 --- a/arch/sparc/kernel/smp.c +++ b/arch/sparc/kernel/smp.c @@ -68,16 +68,6 @@ void __cpuinit smp_store_cpu_info(int id) cpu_data(id).prom_node = cpu_node; cpu_data(id).mid = cpu_get_hwmid(cpu_node); - /* this is required to tune the scheduler correctly */ - /* is it possible to have CPUs with different cache sizes? */ - if (id == boot_cpu_id) { - int cache_line,cache_nlines; - cache_line = 0x20; - cache_line = prom_getintdefault(cpu_node, "ecache-line-size", cache_line); - cache_nlines = 0x8000; - cache_nlines = prom_getintdefault(cpu_node, "ecache-nlines", cache_nlines); - max_cache_size = cache_line * cache_nlines; - } if (cpu_data(id).mid < 0) panic("No MID found for CPU%d at node 0x%08d", id, cpu_node); } -- cgit v1.2.3-70-g09d2