Re: [PATCH v3 1/2] bpf: add a longest prefix match trie map implementation

[David Herrmann <dh.herrmann@gmail.com>]

Hi

On Sat, Jan 14, 2017 at 5:55 PM, Alexei Starovoitov <ast@fb.com> wrote:
> Another alternative is to extend samples/bpf/map_perf_test
> It has perf tests for most map types today (including lru)
> and trie would be natural addition there.
> I would prefer this latter option.

I hooked into gettid() and installed a simple kprobe bpf program that
searches for an entry in an lpm trie. The bpf program does either 0,
1, 8, or 32 lookups in a row (always the same element). The trie has
size 0, 1, or 8192. The data is below. The results vary by roughly 5%
on every run.

A single gettid() syscall with an empty bpf program takes roughly
6.5us on my system. Lookups in empty tries take ~1.8us on first try,
~0.9us on retries. Lookups in tries with 8192 entries take ~7.1us (on
the first _and_ any subsequent try).

https://gist.github.com/dvdhrm/4c90e61a1c39746d5c55ab9e0e29315e

Thanks
David


Trie-size: 0
#Lookups: 0
    0:lpm_perf kmalloc 9,230,321 events per sec
    -> 6.5us / syscall

Trie-size: 1
#Lookups: 1
    0:lpm_perf kmalloc 7,224,508 events per sec
    -> 8.3us / syscall

Trie-size: 1
#Lookups: 8
    0:lpm_perf kmalloc 4,152,740 events per sec
    -> 14.4us / syscall

Trie-size: 1
#Lookups: 32
    0:lpm_perf kmalloc 1,713,415 events per sec
    -> 35.0us / syscall

Trie-size: 8192
#Lookups: 1
    0:lpm_perf kmalloc 4,369,138 events per sec
    -> 13.7us / syscall

Trie-size: 8192
#Lookups: 8
    0:lpm_perf kmalloc 943,849 events per sec
    -> 63.6us / syscall

Trie-size: 8192
#Lookups: 32
    0:lpm_perf kmalloc 271,737 events per sec
    -> 220.8us / syscall