Patch 1: add a selftest app to benchmark the performance of ptr_ring. Patch 2: move r->queue[] clearing after r->consumer_head updating. Patch 3: add barrier to ensure the visiblity of r->queue[].
V3: add patch 3 and address most of Michael's comment. V2: add patch 1 and add performance data for patch 2.
--- Performance raw data using "perf stat -r" cmd, comparison is also done in patch 2/3. ptr_ring_test_org: patch 1 ptr_ring_test_opt1: patch 1 + patch 2 ptr_ring_test_opt2: patch 1 + patch 2 + patch 3
x86_64(as there is other workload in the x86_64 system, so run 1000 times to get more accurate result):
Performance counter stats for './ptr_ring_test_org -s 1000 -m 1 -N 100000000' (1000 runs):
5,291.83 msec task-clock # 1.994 CPUs utilized ( +- 0.41% ) 690 context-switches # 0.130 K/sec ( +- 3.65% ) 8 cpu-migrations # 0.002 K/sec ( +- 5.70% ) 291 page-faults # 0.055 K/sec ( +- 0.05% ) 12,660,040,758 cycles # 2.392 GHz ( +- 0.41% ) 24,202,160,722 instructions # 1.91 insn per cycle ( +- 0.06% ) 3,559,123,597 branches # 672.569 M/sec ( +- 0.07% ) 8,009,010 branch-misses # 0.23% of all branches ( +- 0.11% )
2.6538 +- 0.0109 seconds time elapsed ( +- 0.41% )
Performance counter stats for './ptr_ring_test_opt1 -s 1000 -m 1 -N 100000000' (1000 runs):
5,064.95 msec task-clock # 1.992 CPUs utilized ( +- 0.55% ) 668 context-switches # 0.132 K/sec ( +- 4.20% ) 9 cpu-migrations # 0.002 K/sec ( +- 4.45% ) 291 page-faults # 0.057 K/sec ( +- 0.06% ) 12,117,262,182 cycles # 2.392 GHz ( +- 0.55% ) 22,586,035,716 instructions # 1.86 insn per cycle ( +- 0.08% ) 3,404,652,345 branches # 672.199 M/sec ( +- 0.10% ) 7,864,190 branch-misses # 0.23% of all branches ( +- 0.16% )
2.5422 +- 0.0142 seconds time elapsed ( +- 0.56% )
Performance counter stats for './ptr_ring_test_opt2 -s 1000 -m 1 -N 100000000' (1000 runs):
5,105.33 msec task-clock # 1.995 CPUs utilized ( +- 0.47% ) 589 context-switches # 0.115 K/sec ( +- 4.24% ) 11 cpu-migrations # 0.002 K/sec ( +- 4.24% ) 292 page-faults # 0.057 K/sec ( +- 0.04% ) 12,214,160,307 cycles # 2.392 GHz ( +- 0.47% ) 22,756,292,370 instructions # 1.86 insn per cycle ( +- 0.10% ) 3,429,218,233 branches # 671.694 M/sec ( +- 0.12% ) 7,921,984 branch-misses # 0.23% of all branches ( +- 0.15% )
2.5587 +- 0.0122 seconds time elapsed ( +- 0.47% )
------------------------------------------------------------------------------------------------- arm64(using taskset to avoid the numa effects):
Performance counter stats for 'taskset -c 0-1 ./ptr_ring_test_org -s 1000 -m 1 -N 100000000' (100 runs):
4172.83 msec task-clock # 1.999 CPUs utilized ( +- 0.01% ) 54 context-switches # 0.013 K/sec ( +- 0.29% ) 1 cpu-migrations # 0.000 K/sec 115 page-faults # 0.028 K/sec ( +- 0.16% ) 10848085945 cycles # 2.600 GHz ( +- 0.01% ) 25808501369 instructions # 2.38 insn per cycle ( +- 0.00% ) <not supported> branches 11190266 branch-misses ( +- 0.02% )
2.087205 +- 0.000130 seconds time elapsed ( +- 0.01% )
Performance counter stats for 'taskset -c 0-1 ./ptr_ring_test_opt1 -s 1000 -m 1 -N 100000000' (100 runs):
3774.91 msec task-clock # 1.999 CPUs utilized ( +- 0.03% ) 50 context-switches # 0.013 K/sec ( +- 0.36% ) 1 cpu-migrations # 0.000 K/sec 114 page-faults # 0.030 K/sec ( +- 0.15% ) 9813658996 cycles # 2.600 GHz ( +- 0.03% ) 23920189000 instructions # 2.44 insn per cycle ( +- 0.01% ) <not supported> branches 10018927 branch-misses ( +- 0.04% )
1.888224 +- 0.000541 seconds time elapsed ( +- 0.03% )
Performance counter stats for 'taskset -c 0-1 ./ptr_ring_test_opt2 -s 1000 -m 1 -N 100000000' (100 runs):
3785.79 msec task-clock # 1.999 CPUs utilized ( +- 0.03% ) 49 context-switches # 0.013 K/sec ( +- 0.32% ) 1 cpu-migrations # 0.000 K/sec 114 page-faults # 0.030 K/sec ( +- 0.15% ) 9842067534 cycles # 2.600 GHz ( +- 0.03% ) 24074397270 instructions # 2.45 insn per cycle ( +- 0.01% ) <not supported> branches 10091918 branch-misses ( +- 0.04% )
1.893673 +- 0.000508 seconds time elapsed ( +- 0.03% )
Yunsheng Lin (3): selftests/ptr_ring: add benchmark application for ptr_ring ptr_ring: move r->queue[] clearing after r->consumer_head updating ptr_ring: add barrier to ensure the visiblity of r->queue[]
MAINTAINERS | 5 + include/linux/ptr_ring.h | 52 ++++-- tools/testing/selftests/ptr_ring/Makefile | 6 + tools/testing/selftests/ptr_ring/ptr_ring_test.c | 224 +++++++++++++++++++++++ tools/testing/selftests/ptr_ring/ptr_ring_test.h | 130 +++++++++++++ 5 files changed, 399 insertions(+), 18 deletions(-) create mode 100644 tools/testing/selftests/ptr_ring/Makefile create mode 100644 tools/testing/selftests/ptr_ring/ptr_ring_test.c create mode 100644 tools/testing/selftests/ptr_ring/ptr_ring_test.h