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authorJohn David Anglin <dave.anglin@bell.net>2022-03-11 18:59:12 +0000
committerHelge Deller <deller@gmx.de>2022-03-11 20:19:41 +0100
commita58e9d0984e8dad53f17ec73ae3c1cc7f8d88151 (patch)
treefb6f832c85f8da56fdc1a09d557010eeb197043c /arch/parisc
parente5e9e7f222e5b3da5bc441d315d1ce7b000ed1be (diff)
downloadlinux-a58e9d0984e8dad53f17ec73ae3c1cc7f8d88151.tar.bz2
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.c18
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",