#include #include #include #include #define CREATE_TRACE_POINTS #include "trace_benchmark.h" static struct task_struct *bm_event_thread; static char bm_str[BENCHMARK_EVENT_STRLEN] = "START"; static u64 bm_total; static u64 bm_totalsq; static u64 bm_last; static u64 bm_max; static u64 bm_min; static u64 bm_first; static u64 bm_cnt; static u64 bm_stddev; static unsigned int bm_avg; static unsigned int bm_std; static bool ok_to_run; /* * This gets called in a loop recording the time it took to write * the tracepoint. What it writes is the time statistics of the last * tracepoint write. As there is nothing to write the first time * it simply writes "START". As the first write is cold cache and * the rest is hot, we save off that time in bm_first and it is * reported as "first", which is shown in the second write to the * tracepoint. The "first" field is writen within the statics from * then on but never changes. */ static void trace_do_benchmark(void) { u64 start; u64 stop; u64 delta; u64 stddev; u64 seed; u64 last_seed; unsigned int avg; unsigned int std = 0; /* Only run if the tracepoint is actually active */ if (!trace_benchmark_event_enabled() || !tracing_is_on()) return; local_irq_disable(); start = trace_clock_local(); trace_benchmark_event(bm_str); stop = trace_clock_local(); local_irq_enable(); bm_cnt++; delta = stop - start; /* * The first read is cold cached, keep it separate from the * other calculations. */ if (bm_cnt == 1) { bm_first = delta; scnprintf(bm_str, BENCHMARK_EVENT_STRLEN, "first=%llu [COLD CACHED]", bm_first); return; } bm_last = delta; if (delta > bm_max) bm_max = delta; if (!bm_min || delta < bm_min) bm_min = delta; /* * When bm_cnt is greater than UINT_MAX, it breaks the statistics * accounting. Freeze the statistics when that happens. * We should have enough data for the avg and stddev anyway. */ if (bm_cnt > UINT_MAX) { scnprintf(bm_str, BENCHMARK_EVENT_STRLEN, "last=%llu first=%llu max=%llu min=%llu ** avg=%u std=%d std^2=%lld", bm_last, bm_first, bm_max, bm_min, bm_avg, bm_std, bm_stddev); return; } bm_total += delta; bm_totalsq += delta * delta; if (bm_cnt > 1) { /* * Apply Welford's method to calculate standard deviation: * s^2 = 1 / (n * (n-1)) * (n * \Sum (x_i)^2 - (\Sum x_i)^2) */ stddev = (u64)bm_cnt * bm_totalsq - bm_total * bm_total; do_div(stddev, (u32)bm_cnt); do_div(stddev, (u32)bm_cnt - 1); } else stddev = 0; delta = bm_total; do_div(delta, bm_cnt); avg = delta; if (stddev > 0) { int i = 0; /* * stddev is the square of standard deviation but * we want the actualy number. Use the average * as our seed to find the std. * * The next try is: * x = (x + N/x) / 2 * * Where N is the squared number to find the square * root of. */ seed = avg; do { last_seed = seed; seed = stddev; if (!last_seed) break; do_div(seed, last_seed); seed += last_seed; do_div(seed, 2); } while (i++ < 10 && last_seed != seed); std = seed; } scnprintf(bm_str, BENCHMARK_EVENT_STRLEN, "last=%llu first=%llu max=%llu min=%llu avg=%u std=%d std^2=%lld", bm_last, bm_first, bm_max, bm_min, avg, std, stddev); bm_std = std; bm_avg = avg; bm_stddev = stddev; } static int benchmark_event_kthread(void *arg) { /* sleep a bit to make sure the tracepoint gets activated */ msleep(100); while (!kthread_should_stop()) { trace_do_benchmark(); /* * We don't go to sleep, but let others * run as well. */ cond_resched(); } return 0; } /* * When the benchmark tracepoint is enabled, it calls this * function and the thread that calls the tracepoint is created. */ int trace_benchmark_reg(void) { if (!ok_to_run) { pr_warning("trace benchmark cannot be started via kernel command line\n"); return -EBUSY; } bm_event_thread = kthread_run(benchmark_event_kthread, NULL, "event_benchmark"); if (!bm_event_thread) { pr_warning("trace benchmark failed to create kernel thread\n"); return -ENOMEM; } return 0; } /* * When the benchmark tracepoint is disabled, it calls this * function and the thread that calls the tracepoint is deleted * and all the numbers are reset. */ void trace_benchmark_unreg(void) { if (!bm_event_thread) return; kthread_stop(bm_event_thread); bm_event_thread = NULL; strcpy(bm_str, "START"); bm_total = 0; bm_totalsq = 0; bm_last = 0; bm_max = 0; bm_min = 0; bm_cnt = 0; /* These don't need to be reset but reset them anyway */ bm_first = 0; bm_std = 0; bm_avg = 0; bm_stddev = 0; } static __init int ok_to_run_trace_benchmark(void) { ok_to_run = true; return 0; } early_initcall(ok_to_run_trace_benchmark); tion>mode:
Diffstat (limited to 'include/net/tc_act/tc_connmark.h')