On 2021-05-12 6:43 p.m., Jamal Hadi Salim wrote:
Will run some tests tomorrow to see the effect of batching vs nobatch
and capture cost of syscalls and cpu.
So here are some numbers:
Processor: Intel(R) Xeon(R) Gold 6230R CPU @ 2.10GHz
This machine is very similar to where a real deployment
would happen.
Hyperthreading turned off so we can dedicate the core to the
dumping process and Performance mode on, so no frequency scaling
meddling.
Tests were ran about 3 times each. Results eye-balled to make
sure deviation was reasonable.
100% of the one core was used just for dumping during each run.
bpftool does linear retrieval whereas our tool does batch dumping.
bpftool does print the dumped results, for our tool we just count
the number of entries retrieved (cost would have been higher if
we actually printed). In any case in the real setup there is
a processing cost which is much higher.
Summary is: the dumping is problematic costwise as the number of
entries increase. While batching does improve things it doesnt
solve our problem (Like i said we have upto 16M entries and most
of the time we are dumping useless things)
1M entries
----------
root@SUT:/home/jhs/git-trees/ftables/src# time ./ftables show system
cache dev enp179s0f1 > /dev/null
real 0m0.320s
user 0m0.004s
sys 0m0.316s
root@SUT:/home/jhs/git-trees/ftables/src# time
/home/jhs/git-trees/foobar/XDP/bpftool map dump id 3353 > /dev/null
real 0m5.419s
user 0m4.347s
sys 0m1.072s
4M entries
-----------
root@SUT:/home/jhs/git-trees/ftables/src# time ./ftables show system cache
dev enp179s0f1 > /dev/null
real 0m1.331s
user 0m0.004s
sys 0m1.325s
root@SUT:/home/jhs/git-trees/ftables/src# time
/home/jhs/git-trees/foobar/XDP/bpftool map dump id 1178 > /dev/null
real 0m21.677s
user 0m17.269s
sys 0m4.408s
8M Entries
------------
root@SUT:/home/jhs/git-trees/ftables/src# time ./ftables show system
cache dev enp179s0f1 > /dev/null
real 0m2.678s
user 0m0.004s
sys 0m2.672s
t@SUT:/home/jhs/git-trees/ftables/src# time
/home/jhs/git-trees/foobar/XDP/bpftool map dump id 2636 > /dev/null
real 0m43.267s
user 0m34.450s
sys 0m8.817s
16M entries
------------
root@SUT:/home/jhs/git-trees/ftables/src# time ./ftables show system cache
dev enp179s0f1 > /dev/null
real 0m5.396s
user 0m0.004s
sys 0m5.389s
root@SUT:/home/jhs/git-trees/ftables/src# time
/home/jhs/git-trees/foobar/XDP/bpftool map dump id 1919 > /dev/null
real 1m27.039s
user 1m8.371s
sys 0m18.668s
cheers,
jamal
