[PATCH] powerpc/8xx: Use 8MB D-TLB's for kernel static mapping faults
The following implements support for instantiation of 8MB D-TLB
entries for the kernel direct virtual mapping on 8xx, thus reducing TLB
space consumed for the kernel.
Test used: writing 40MB from /dev/zero to file in ext2fs over
RAMDISK.
$ time dd if=/dev/zero of=file bs=4k count=10000
VANILLA 8MB kernel data pages
real 0m11.485s real 0m11.267s
user 0m0.218s user 0m0.250s
sys 0m8.939s sys 0m9.108s
real 0m11.518s real 0m10.978s
user 0m0.203s user 0m0.222s
sys 0m9.585s sys 0m9.138s
real 0m11.554s real 0m10.967s
user 0m0.228s user 0m0.222s
sys 0m9.497s sys 0m9.127s
real 0m11.633s real 0m11.286s
user 0m0.214s user 0m0.196s
sys 0m9.529s sys 0m9.134s
and averages for both:
real 11.54750 real 11.12450
Which is a 3.6% improvement in execution time. More improvement is
expected for loads with larger kernel data footprint (real workloads).
Signed-off-by: Marcelo Tosatti <marcelo.tosatti@cyclades.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
1 file changed