Commit a58e9d09 authored by John David Anglin's avatar John David Anglin Committed by Helge Deller
Browse files

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: default avatarJohn David Anglin <dave.anglin@bell.net>
Signed-off-by: default avatarHelge Deller <deller@gmx.de>
parent e5e9e7f2

arch/parisc/kernel/cache.c

+15 −3
Original line number Diff line number Diff line
@@ -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",