From: David S. Miller Date: Sat, 6 Feb 2016 08:34:46 +0000 (-0500) Subject: Merge branch 'bpf-per-cpu-maps' X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=8ac2c867b516268fd8797ad7c7375c71419714ea;p=linux-beck.git Merge branch 'bpf-per-cpu-maps' Alexei Starovoitov says: ==================== bpf: introduce per-cpu maps We've started to use bpf to trace every packet and atomic add instruction (event JITed) started to show up in perf profile. The solution is to do per-cpu counters. For PERCPU_(HASH|ARRAY) map the existing bpf_map_lookup() helper returns per-cpu area which bpf programs can use to store and increment the counters. The BPF_MAP_LOOKUP_ELEM syscall command returns areas from all cpus and user process aggregates the counters. The usage example is in patch 6. The api turned out to be very easy to use from bpf program and from user space. Long term we were discussing to add 'bounded loop' instruction, so bpf programs can do aggregation within the program which may help some use cases. Right now user space aggregation of per-cpu counters fits the best. This patch set is new approach for per-cpu hash and array maps. I've reused the map tests written by Martin and Ming, but implementation and api is new. Old discussion here: http://thread.gmane.org/gmane.linux.kernel/2123800/focus=2126435 ==================== Signed-off-by: David S. Miller --- 8ac2c867b516268fd8797ad7c7375c71419714ea