diff options
| author | John David Anglin <dave.anglin@bell.net> | 2022-03-11 18:59:12 +0000 |
|---|---|---|
| committer | Helge Deller <deller@gmx.de> | 2022-03-11 20:19:41 +0100 |
| commit | a58e9d0984e8dad53f17ec73ae3c1cc7f8d88151 (patch) | |
| tree | fb6f832c85f8da56fdc1a09d557010eeb197043c /arch/parisc | |
| parent | e5e9e7f222e5b3da5bc441d315d1ce7b000ed1be (diff) | |
parisc: Increase parisc_cache_flush_threshold setting
In testing the "Fix non-access data TLB cache flush faults" change,
I noticed a significant improvement in glibc build and check times.
This led me to investigate the parisc_cache_flush_threshold setting.
It determines when we switch from line flushing to whole cache flushing.
It turned out that the parisc_cache_flush_threshold setting on
mako and mako2 machines (PA8800 and PA8900 processors) was way too
small. Adjusting this setting provided almost a factor two improvement
in the glibc build and check time.
Signed-off-by: John David Anglin <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>
Diffstat (limited to 'arch/parisc')
| -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", |