diff options
Diffstat (limited to 'arch/parisc/kernel/cache.c')
| -rw-r--r-- | arch/parisc/kernel/cache.c | 18 |
1 files changed, 15 insertions, 3 deletions
diff --git a/arch/parisc/kernel/cache.c b/arch/parisc/kernel/cache.c index 59c2d079f178..81f36d6407f0 100644 --- a/arch/parisc/kernel/cache.c +++ b/arch/parisc/kernel/cache.c @@ -388,7 +388,7 @@ void __init parisc_setup_cache_timing(void) { unsigned long rangetime, alltime; unsigned long size; - unsigned long threshold; + unsigned long threshold, threshold2; alltime = mfctl(16); flush_data_cache(); @@ -403,8 +403,20 @@ void __init parisc_setup_cache_timing(void) alltime, size, rangetime); threshold = L1_CACHE_ALIGN(size * alltime / rangetime); - if (threshold > cache_info.dc_size) - threshold = cache_info.dc_size; + + /* + * The threshold computed above isn't very reliable since the + * flush times depend greatly on the percentage of dirty lines + * in the flush range. Further, the whole cache time doesn't + * include the time to refill lines that aren't in the mm/vma + * being flushed. By timing glibc build and checks on mako cpus, + * the following formula seems to work reasonably well. The + * value from the timing calculation is too small, and increases + * build and check times by almost a factor two. + */ + threshold2 = cache_info.dc_size * num_online_cpus(); + if (threshold2 > threshold) + threshold = threshold2; if (threshold) parisc_cache_flush_threshold = threshold; printk(KERN_INFO "Cache flush threshold set to %lu KiB\n", |