Thread (25 messages) flat view 25 messages, 8 authors, 2017-10-26

Re: [net-next V4 PATCH 2/5] bpf: XDP_REDIRECT enable use of cpumap

From: Jesper Dangaard Brouer <hidden>
Date: 2017-10-06 15:46:03

On Fri, 6 Oct 2017 13:17:48 +0200
Jesper Dangaard Brouer [off-list ref] wrote:
quoted
quoted
+static void *__xdp_map_lookup_elem(struct bpf_map *map, u32 index)
+{
+	switch (map->map_type) {
+	case BPF_MAP_TYPE_DEVMAP:
+		return __dev_map_lookup_elem(map, index);
+	case BPF_MAP_TYPE_CPUMAP:
+		return __cpu_map_lookup_elem(map, index);
+	default:
+		return NULL;
+	}    
Should we just have a callback and instead of the above use
map->ptr_lookup_elem() (or however we name it) ... lot of it
is pretty much the same logic as with devmap.  
We could extend struct bpf_map *map with such a callback, I was just
afraid that this would be too invasive.

Performance wise, I don't thinks will hurt too much.
http://www.cipht.net/2017/10/03/are-jump-tables-always-fastest.html
Looking at the code, I would like to postpone this callback work until
after this patchset is merged.  As this work will also touch devmap +
sockmap.

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer
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