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authorIngo Molnar <mingo@elte.hu>2007-07-09 18:51:57 +0200
committerIngo Molnar <mingo@elte.hu>2007-07-09 18:51:57 +0200
commit0437e109e1841607f2988891eaa36c531c6aa6ac (patch)
treee9d8f170786f7e33d4c5829cb008cf38d42a2014 /arch/sparc64
parent0e6aca43e08a62a48d6770e9a159dbec167bf4c6 (diff)
downloadlinux-2.6.34-ux500-0437e109e1841607f2988891eaa36c531c6aa6ac.tar.gz
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 <mingo@elte.hu>
Diffstat (limited to 'arch/sparc64')
-rw-r--r--arch/sparc64/kernel/smp.c27
1 files changed, 0 insertions, 27 deletions
diff --git a/arch/sparc64/kernel/smp.c b/arch/sparc64/kernel/smp.c
index 4dcd7d0b60f..40e40f968d6 100644
--- a/arch/sparc64/kernel/smp.c
+++ b/arch/sparc64/kernel/smp.c
@@ -1163,32 +1163,6 @@ int setup_profiling_timer(unsigned int multiplier)
return -EINVAL;
}
-static void __init smp_tune_scheduling(void)
-{
- unsigned int smallest = ~0U;
- int i;
-
- for (i = 0; i < NR_CPUS; i++) {
- unsigned int val = cpu_data(i).ecache_size;
-
- if (val && val < smallest)
- smallest = val;
- }
-
- /* Any value less than 256K is nonsense. */
- if (smallest < (256U * 1024U))
- smallest = 256 * 1024;
-
- max_cache_size = smallest;
-
- if (smallest < 1U * 1024U * 1024U)
- printk(KERN_INFO "Using max_cache_size of %uKB\n",
- smallest / 1024U);
- else
- printk(KERN_INFO "Using max_cache_size of %uMB\n",
- smallest / 1024U / 1024U);
-}
-
/* Constrain the number of cpus to max_cpus. */
void __init smp_prepare_cpus(unsigned int max_cpus)
{
@@ -1206,7 +1180,6 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
}
cpu_data(boot_cpu_id).udelay_val = loops_per_jiffy;
- smp_tune_scheduling();
}
void __devinit smp_prepare_boot_cpu(void)