[PATCH] powerpc/8xx: Use 8MB D-TLB's for kernel static mapping faults
authorMarcelo Tosatti <marcelo.tosatti@cyclades.com>
Fri, 13 Jan 2006 16:16:12 +0000 (14:16 -0200)
committerPaul Mackerras <paulus@samba.org>
Sat, 14 Jan 2006 00:14:27 +0000 (11:14 +1100)
commit8f069b1a90bd97bf6d59a02ecabf0173d9175609
tree8853964c83300fa58f5ae7c932cdb44ee89e3da8
parent7d13d21ae85f64e35dcdae4d6a6286e62a38e0ab
[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>
arch/ppc/kernel/head_8xx.S