# \[PATCH net-next 0/4\] bpf: bpf\_htab: Add BPF\_MAP\_TYPE\_PERCPU\_HASH

- From: Martin KaFai Lau \<hidden\>
- Date: 2016-01-07 22:36:20 
- List: netdev
- Page: https://ratatoskr.run/netdev/2016/01/4655222
- Thread: https://ratatoskr.run/netdev/2016/01/4655222/t.md

```text
This patchset adds BPF_MAP_TYPE_PERCPU_HASH map type which allows
percpu value.

BPF + kprobe is very useful in statistics collection.  In particular,
bpf is strong in doing aggregation within the kernel instead of
outputting a lot of raw samples to the userspace.

In some cases, bumping a counter/value of a particular key will have
noticeable impact.  For example, doing statistics collection
on received packets and aggregating them by network
prefix (like /64 in IPv6).  Having a percpu value can help.
```