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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>
This commit is contained in:
John David Anglin 2022-03-11 18:59:12 +00:00 committed by Helge Deller
parent e5e9e7f222
commit a58e9d0984
1 changed files with 15 additions and 3 deletions
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18
arch/parisc/kernel/cache.c
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@ -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",