kernel/tools/testing/selftests/bpf/test_lru_map.c, branch linux-4.16.y

bpf: lru: Lower the PERCPU_NR_SCANS from 16 to 4

2017-04-17T17:55:52Z

After doing map_perf_test with a much bigger BPF_F_NO_COMMON_LRU map, the perf report shows a lot of time spent in rotating the inactive list (i.e. __bpf_lru_list_rotate_inactive): > map_perf_test 32 8 10000 1000000 | awk '{sum += $3}END{print sum}' 19644783 (19M/s) > map_perf_test 32 8 10000000 10000000 | awk '{sum += $3}END{print sum}' 6283930 (6.28M/s) By inactive, it usually means the element is not in cache. Hence, there is a need to tune the PERCPU_NR_SCANS value. This patch finds a better number of elements to scan during each list rotation. The PERCPU_NR_SCANS (which is defined the same as PERCPU_FREE_TARGET) decreases from 16 elements to 4 elements. This change only affects the BPF_F_NO_COMMON_LRU map. The test_lru_dist does not show meaningful difference between 16 and 4. Our production L4 load balancer which uses the LRU map for conntrack-ing also shows little change in cache hit rate. Since both benchmark and production data show no cache-hit difference, PERCPU_NR_SCANS is lowered from 16 to 4. We can consider making it configurable if we find a usecase later that shows another value works better and/or use a different rotation strategy. After this change: > map_perf_test 32 8 10000000 10000000 | awk '{sum += $3}END{print sum}' 9240324 (9.2M/s) i.e. 6.28M/s -> 9.2M/s The test_lru_dist has not shown meaningful difference: > test_lru_dist zipf.100k.a1_01.out 4000 1: nr_misses: 31575 (Before) vs 31566 (After) > test_lru_dist zipf.100k.a0_01.out 40000 1 nr_misses: 67036 (Before) vs 67031 (After) Signed-off-by: Martin KaFai Lau Acked-by: Alexei Starovoitov Acked-by: Daniel Borkmann Signed-off-by: David S. Miller

bpf: lru: Cleanup test_lru_map.c

2017-04-17T17:55:52Z

This patch does the following cleanup on test_lru_map.c 1) Fix indentation (Replace spaces by tabs) 2) Remove redundant BPF_F_NO_COMMON_LRU test 3) Simplify some comments Signed-off-by: Martin KaFai Lau Acked-by: Alexei Starovoitov Acked-by: Daniel Borkmann Signed-off-by: David S. Miller

bpf: lru: Add test_lru_sanity6 for BPF_F_NO_COMMON_LRU

2017-04-17T17:55:52Z

test_lru_sanity3 is not applicable to BPF_F_NO_COMMON_LRU. It just happens to work when PERCPU_FREE_TARGET == 16. This patch: 1) Disable test_lru_sanity3 for BPF_F_NO_COMMON_LRU 2) Add test_lru_sanity6 to test list rotation for the BPF_F_NO_COMMON_LRU map. Signed-off-by: Martin KaFai Lau Acked-by: Alexei Starovoitov Acked-by: Daniel Borkmann Signed-off-by: David S. Miller

bpf: Remove bpf_sys.h from selftests

2017-02-10T20:56:08Z

Add require dependency headers. Signed-off-by: Mickaël Salaün Cc: Alexei Starovoitov Cc: Daniel Borkmann Cc: Shuah Khan Signed-off-by: David S. Miller

bpf: Use bpf_create_map() from the library

2017-02-10T20:56:07Z

Replace bpf_map_create() with bpf_create_map() calls. Signed-off-by: Mickaël Salaün Cc: Alexei Starovoitov Cc: Daniel Borkmann Cc: Shuah Khan Signed-off-by: David S. Miller

bpf: Use bpf_map_get_next_key() from the library

2017-02-10T20:56:07Z

Replace bpf_map_next_key() with bpf_map_get_next_key() calls. Signed-off-by: Mickaël Salaün Cc: Alexei Starovoitov Cc: Daniel Borkmann Cc: Shuah Khan Signed-off-by: David S. Miller

bpf: Use bpf_map_delete_elem() from the library

2017-02-10T20:56:07Z

Replace bpf_map_delete() with bpf_map_delete_elem() calls. Signed-off-by: Mickaël Salaün Cc: Alexei Starovoitov Cc: Daniel Borkmann Cc: Shuah Khan Signed-off-by: David S. Miller

bpf: Use bpf_map_lookup_elem() from the library

2017-02-10T20:56:07Z

Replace bpf_map_lookup() with bpf_map_lookup_elem() calls. Signed-off-by: Mickaël Salaün Cc: Alexei Starovoitov Cc: Daniel Borkmann Cc: Shuah Khan Signed-off-by: David S. Miller

bpf: Use bpf_map_update_elem() from the library

2017-02-10T20:56:07Z

Replace bpf_map_update() with bpf_map_update_elem() calls. Signed-off-by: Mickaël Salaün Cc: Alexei Starovoitov Cc: Daniel Borkmann Cc: Shuah Khan Signed-off-by: David S. Miller

bpf: Fix test_lru_sanity5() in test_lru_map.c

2017-01-17T20:39:39Z

test_lru_sanity5() fails when the number of online cpus is fewer than the number of possible cpus. It can be reproduced with qemu by using cmd args "--smp cpus=2,maxcpus=8". The problem is the loop in test_lru_sanity5() is testing 'i' which is incorrect. This patch: 1. Make sched_next_online() always return -1 if it cannot find a next cpu to schedule the process. 2. In test_lru_sanity5(), the parent process does sched_setaffinity() first (through sched_next_online()) and the forked process will inherit it according to the 'man sched_setaffinity'. Fixes: 5db58faf989f ("bpf: Add tests for the LRU bpf_htab") Reported-by: Daniel Borkmann Signed-off-by: Martin KaFai Lau Acked-by: Daniel Borkmann Acked-by: Alexei Starovoitov Signed-off-by: David S. Miller