After another round of performance tuning HAMMER all my benchmarks
show HAMMER within 10% of UFS's performance, and it beats the shit
out of UFS in certain tests such as file creation and random write
performance. Read performance is good but drops more then UFS under
heavy write loads (but write performance is much better at the same
time).
I am making progress with blogbench. It turns out that HAMMER isn't
quite as horrible as it first appeared. What was happening was simply
that the test under UFS never got past blog #200, and thus never wrote
enough data to blow out the system caches. The blogbench test builds
up an ever-increasing sized dataset as it progresses.
HAMMER has superior random write performance and because of that it
easily got into the blog #350-400 range in the default test, or about
double the size of the data-set. Plus it was writing more
during the first half of the test so that of course depressed the
read performance a bit relative to UFS.
When I increase the number of iterations sufficiently for both UFS and
HAMMER to blow out the system caches, the results wind up being very
different.
blogbench --iterations=100 -d /mnt/bench2
Now when UFS gets past blog #300 and blows out the system caches, UFS's
write performance goes completely to hell but it is able to maintain
good read performance:
Nb blogs R articles W articles R pictures W pictures R comments W comments
322 72232 67 55654 88 45740 194
323 83711 81 64882 81 53844 204
325 57380 62 43314 62 36603 196
...
345 17494 40 12866 50 12226 137
347 21895 42 16655 41 13002 128
347 22803 68 17517 12 14247 122
348 16976 52 13397 29 12113 119
...
