Le 10/02/2018 à 09:11, Nicholas Piggin a écrit :
This series intends to improve performance and reduce stack
consumption in the slice allocation code. It does it by keeping slice
masks in the mm_context rather than compute them for each allocation,
and by reducing bitmaps and slice_masks from stacks, using pointers
instead where possible.
checkstack.pl gives, before:
0x00000de4 slice_get_unmapped_area [slice.o]: 656
0x00001b4c is_hugepage_only_range [slice.o]: 512
0x0000075c slice_find_area_topdown [slice.o]: 416
0x000004c8 slice_find_area_bottomup.isra.1 [slice.o]: 272
0x00001aa0 slice_set_range_psize [slice.o]: 240
0x00000a64 slice_find_area [slice.o]: 176
0x00000174 slice_check_fit [slice.o]: 112
after:
0x00000d70 slice_get_unmapped_area [slice.o]: 320
0x000008f8 slice_find_area [slice.o]: 144
0x00001860 slice_set_range_psize [slice.o]: 144
0x000018ec is_hugepage_only_range [slice.o]: 144
0x00000750 slice_find_area_bottomup.isra.4 [slice.o]: 128
The benchmark in https://github.com/linuxppc/linux/issues/49 gives, before:
$ time ./slicemask
real 0m20.712s
user 0m5.830s
sys 0m15.105s
after:
$ time ./slicemask
real 0m13.197s
user 0m5.409s
sys 0m7.779s
Hi,
I tested your serie on an 8xx, on top of patch
https://patchwork.ozlabs.org/patch/871675/
I don't get a result as significant as yours, but there is some
improvment anyway:
ITERATION 500000
Before:
root@vgoip:~# time ./slicemask
real 0m 33.26s
user 0m 1.94s
sys 0m 30.85s
After:
root@vgoip:~# time ./slicemask
real 0m 29.69s
user 0m 2.11s
sys 0m 27.15s
Most significant improvment is obtained with the first patch of your serie:
root@vgoip:~# time ./slicemask
real 0m 30.85s
user 0m 1.80s
sys 0m 28.57s
Had to modify your serie a bit, if you are interested I can post it.
Christophe
Thanks,
Nick
Nicholas Piggin (5):
powerpc/mm/slice: pass pointers to struct slice_mask where possible
powerpc/mm/slice: implement a slice mask cache
powerpc/mm/slice: implement slice_check_range_fits
powerpc/mm/slice: Use const pointers to cached slice masks where
possible
powerpc/mm/slice: use the dynamic high slice size to limit bitmap
operations
arch/powerpc/include/asm/book3s/64/mmu.h | 20 +-
arch/powerpc/mm/slice.c | 302 +++++++++++++++++++------------
2 files changed, 204 insertions(+), 118 deletions(-)
