Just some experiments with spinlocks, done in C99. Using this excellent playlist by CoffeeBeforeArch on youtube.
You'll need to install Nix to try these. I tried to install the perf command with apt and failed miserably. Nix makes that easy plus with nix-shell it's only available for this project.
Then do:
$ nix-shell
make spinlock
spinlock-bench ./spinlock.o
The count is: 100000
real 0m0.009s
user 0m0.005s
sys 0m0.004s
The count is: 200000
real 0m0.023s
user 0m0.044s
sys 0m0.000s
The count is: 400000
real 0m0.103s
user 0m0.392s
sys 0m0.000s
The count is: 800000
real 0m0.478s
user 0m3.658s
sys 0m0.000s
spinlock-stat ./spinlock.o
The count is: 800000
Performance counter stats for './spinlock.o 8':
3,971.95 msec task-clock:u # 7.469 CPUs utilized
0 context-switches:u # 0.000 K/sec
0 cpu-migrations:u # 0.000 K/sec
71 page-faults:u # 0.018 K/sec
8,174,888,035 cycles:u # 2.058 GHz (61.85%)
68,128,831 instructions:u # 0.01 insn per cycle (74.56%)
18,262,842 branches:u # 4.598 M/sec (74.78%)
832,278 branch-misses:u # 4.56% of all branches (75.25%)
19,736,218 L1-dcache-loads:u # 4.969 M/sec (75.59%)
8,759,096 L1-dcache-load-misses:u # 44.38% of all L1-dcache hits (75.64%)
1,235,026 LLC-loads:u # 0.311 M/sec (49.92%)
252 LLC-load-misses:u # 0.02% of all LL-cache hits (49.59%)
0.531788030 seconds time elapsed
3.969189000 seconds user
0.004009000 seconds sys
make spinlockally
spinlock-bench ./spinlockally.o
The count is: 100000
real 0m0.004s
user 0m0.004s
sys 0m0.000s
The count is: 200000
real 0m0.023s
user 0m0.044s
sys 0m0.000s
The count is: 400000
real 0m0.083s
user 0m0.323s
sys 0m0.000s
The count is: 800000
real 0m0.219s
user 0m1.668s
sys 0m0.004s
spinlock-stat ./spinlockally.o
The count is: 800000
Performance counter stats for './spinlockally.o 8':
2,151.71 msec task-clock:u # 7.687 CPUs utilized
0 context-switches:u # 0.000 K/sec
0 cpu-migrations:u # 0.000 K/sec
74 page-faults:u # 0.034 K/sec
4,460,741,205 cycles:u # 2.073 GHz (61.42%)
807,699,645 instructions:u # 0.18 insn per cycle (74.35%)
269,623,840 branches:u # 125.307 M/sec (74.48%)
3,527,201 branch-misses:u # 1.31% of all branches (75.47%)
267,746,311 L1-dcache-loads:u # 124.434 M/sec (76.45%)
11,623,242 L1-dcache-load-misses:u # 4.34% of all L1-dcache hits (76.58%)
7,881,325 LLC-loads:u # 3.663 M/sec (49.73%)
4 LLC-load-misses:u # 0.00% of all LL-cache hits (48.78%)
0.279924663 seconds time elapsed
2.149269000 seconds user
0.004017000 seconds sys
make spinlock_active_backoff
spinlock-bench ./spinlock_active_backoff.o
The count is: 100000
real 0m0.005s
user 0m0.005s
sys 0m0.000s
The count is: 200000
real 0m0.012s
user 0m0.020s
sys 0m0.000s
The count is: 400000
real 0m0.033s
user 0m0.126s
sys 0m0.000s
The count is: 800000
real 0m0.123s
user 0m0.894s
sys 0m0.000s
make spinlock_passive_backoff
spinlock-bench ./spinlock_passive_backoff.o
The count is: 100000
real 0m0.005s
user 0m0.005s
sys 0m0.000s
The count is: 200000
real 0m0.018s
user 0m0.034s
sys 0m0.000s
The count is: 400000
real 0m0.040s
user 0m0.156s
sys 0m0.000s
The count is: 800000
real 0m0.117s
user 0m0.875s
sys 0m0.000s
make spinlock_pthread
spinlock-bench ./spinlock_pthread.o
The count is: 100000
real 0m0.002s
user 0m0.002s
sys 0m0.000s
The count is: 200000
real 0m0.005s
user 0m0.008s
sys 0m0.000s
The count is: 400000
real 0m0.017s
user 0m0.051s
sys 0m0.004s
The count is: 800000
real 0m0.040s
user 0m0.252s
sys 0m0.000s
make spinlock_exp_backoff
spinlock-bench ./spinlock_exp_backoff.o
The count is: 100000
real 0m0.006s
user 0m0.006s
sys 0m0.000s
The count is: 200000
real 0m0.012s
user 0m0.014s
sys 0m0.005s
The count is: 400000
real 0m0.012s
user 0m0.039s
sys 0m0.000s
The count is: 800000
real 0m0.018s
user 0m0.102s
sys 0m0.000s