Brice Goglin wrote:
Stefan Lankes wrote:
I am not able to reconstruct any performance drawbacks on my system.
Could you send me your low-level benchmark?
It's attached. As you may see, it's fairly trivial. It just does several
iterations of mbind+touch_all_pages for different power-of-two buffer
sizes. Just replace mbind with madvise in the inner loop if you want to
try with your affinit-on-next-touch.
I use MPOL_NOOP instead of MPOL_PREFERRED. On my system, MPOL_NOOP is
defined in as 4 (-> include/linux/mempolicy.h).
By the way, do you also add Lee's "shared policy" patches? These patches
add MPOL_MF_SHARED, which is specified as 3. Afterwards, you have to
define MPOL_MF_LAZY as 4.
I got following performance results with MPOL_NOOP:
# Nb_pages Cost(ns)
2 44539
4 44695
8 53937
16 61625
32 87757
64 135070
128 233812
256 428539
512 870476
1024 1695859
2048 3280695
4096 6450328
8192 12719187
16384 25377750
32768 50431375
65536 101970000
131072 216200500
262144 511706000
I got following performance results with MPOL_PREFERRED:
# Nb_pages Cost(ns)
2 50742
4 58656
8 79929
16 117171
32 195304
64 354851
128 744835
256 1354476
512 2759570
1024 5433304
2048 10173390
4096 20178453
8192 36452343
16384 71077375
32768 141738000
65536 281460250
131072 576971000
262144 1231694000
Which kernels are you using when comparing your next-touch
implementation with Lee's patchset?
The current mmotm tree.
Regards,
Stefan
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