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metrics: Use N_EWMA for moving avg, with N=100.

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Part of #40708.
This commit is contained in:
Mike Perry 2022-11-08 19:02:57 +00:00 committed by David Goulet
parent 59bef48490
commit 09d32ac667
4 changed files with 36 additions and 41 deletions
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12
src/core/or/circuitlist.c
View File

@ -154,10 +154,6 @@ double cc_stats_circ_close_cwnd_ma = 0;
/** Moving average of the cc->cwnd from each closed slow-start circuit. */
double cc_stats_circ_close_ss_cwnd_ma = 0;
/* Running count of the above moving averages. Needed so we can update it. */
static double stats_circ_close_cwnd_ma_count = 0;
static double stats_circ_close_ss_cwnd_ma_count = 0;
/********* END VARIABLES ************/
/* Implement circuit handle helpers. */
@ -2244,18 +2240,14 @@ circuit_mark_for_close_, (circuit_t *circ, int reason, int line,
* and a max RTT, and they are not the same. This prevents us from
* averaging and reporting unused and low-use circuits here */
if (circ->ccontrol->max_rtt_usec != circ->ccontrol->min_rtt_usec) {
stats_circ_close_ss_cwnd_ma_count++;
cc_stats_circ_close_ss_cwnd_ma =
stats_update_running_avg(cc_stats_circ_close_ss_cwnd_ma,
circ->ccontrol->cwnd,
stats_circ_close_ss_cwnd_ma_count);
circ->ccontrol->cwnd);
}
} else {
stats_circ_close_cwnd_ma_count++;
cc_stats_circ_close_cwnd_ma =
stats_update_running_avg(cc_stats_circ_close_cwnd_ma,
circ->ccontrol->cwnd,
stats_circ_close_cwnd_ma_count);
circ->ccontrol->cwnd);
}
}

10
src/core/or/congestion_control_flow.c
View File

@ -41,9 +41,7 @@ static uint32_t xon_rate_bytes;
uint64_t cc_stats_flow_num_xoff_sent;
uint64_t cc_stats_flow_num_xon_sent;
double cc_stats_flow_xoff_outbuf_ma = 0;
static double cc_stats_flow_xoff_outbuf_ma_count = 0;
double cc_stats_flow_xon_outbuf_ma = 0;
static double cc_stats_flow_xon_outbuf_ma_count = 0;
/* In normal operation, we can get a burst of up to 32 cells before returning
* to libevent to flush the outbuf. This is a heuristic from hardcoded values
@ -485,11 +483,9 @@ flow_control_decide_xoff(edge_connection_t *stream)
total_buffered, buffer_limit_xoff);
tor_trace(TR_SUBSYS(cc), TR_EV(flow_decide_xoff_sending), stream);
cc_stats_flow_xoff_outbuf_ma_count++;
cc_stats_flow_xoff_outbuf_ma =
stats_update_running_avg(cc_stats_flow_xoff_outbuf_ma,
total_buffered,
cc_stats_flow_xoff_outbuf_ma_count);
total_buffered);
circuit_send_stream_xoff(stream);
@ -646,11 +642,9 @@ flow_control_decide_xon(edge_connection_t *stream, size_t n_written)
total_buffered);
tor_trace(TR_SUBSYS(cc), TR_EV(flow_decide_xon_rate_change), stream);
cc_stats_flow_xon_outbuf_ma_count++;
cc_stats_flow_xon_outbuf_ma =
stats_update_running_avg(cc_stats_flow_xon_outbuf_ma,
total_buffered,
cc_stats_flow_xon_outbuf_ma_count);
total_buffered);
circuit_send_stream_xon(stream);
}

25
src/core/or/congestion_control_vegas.c
View File

@ -56,12 +56,6 @@ double cc_stats_vegas_gamma_drop_ma = 0;
double cc_stats_vegas_delta_drop_ma = 0;
double cc_stats_vegas_ss_csig_blocked_ma = 0;
double cc_stats_vegas_csig_blocked_ma = 0;
/* Running count of this moving average. Needed so we can update it. */
static double stats_cwnd_exit_ss_ma_count = 0;
static double stats_cwnd_gamma_drop_ma_count = 0;
static double stats_cwnd_delta_drop_ma_count = 0;
static double stats_ss_csig_blocked_ma_count = 0;
static double stats_csig_blocked_ma_count = 0;
/** Stats on how many times we reached "delta" param. */
uint64_t cc_stats_vegas_above_delta = 0;
@ -263,10 +257,9 @@ congestion_control_vegas_exit_slow_start(const circuit_t *circ,
congestion_control_vegas_log(circ, cc);
/* Update running cc->cwnd average for metrics. */
stats_cwnd_exit_ss_ma_count++;
cc_stats_vegas_exit_ss_cwnd_ma =
stats_update_running_avg(cc_stats_vegas_exit_ss_cwnd_ma,
cc->cwnd, stats_cwnd_exit_ss_ma_count);
cc->cwnd);
/* We need to report that slow start has exited ASAP,
* for sbws bandwidth measurement. */
@ -347,21 +340,19 @@ congestion_control_vegas_process_sendme(congestion_control_t *cc,
/* Account the amount we reduced the cwnd by for the gamma cutoff */
cwnd_diff = (old_cwnd > cc->cwnd ? old_cwnd - cc->cwnd : 0);
stats_cwnd_gamma_drop_ma_count++;
cc_stats_vegas_gamma_drop_ma =
stats_update_running_avg(cc_stats_vegas_gamma_drop_ma,
cwnd_diff, stats_cwnd_gamma_drop_ma_count);
cwnd_diff);
stats_ss_csig_blocked_ma_count++;
/* Compute the percentage we experience a blocked csig vs RTT sig */
if (cc->blocked_chan) {
cc_stats_vegas_ss_csig_blocked_ma =
stats_update_running_avg(cc_stats_vegas_ss_csig_blocked_ma,
100, stats_ss_csig_blocked_ma_count);
100);
} else {
cc_stats_vegas_ss_csig_blocked_ma =
stats_update_running_avg(cc_stats_vegas_ss_csig_blocked_ma,
0, stats_ss_csig_blocked_ma_count);
0);
}
congestion_control_vegas_exit_slow_start(circ, cc);
@ -384,23 +375,21 @@ congestion_control_vegas_process_sendme(congestion_control_t *cc,
/* Account the amount we reduced the cwnd by for the gamma cutoff */
cwnd_diff = (old_cwnd > cc->cwnd ? old_cwnd - cc->cwnd : 0);
stats_cwnd_delta_drop_ma_count++;
cc_stats_vegas_delta_drop_ma =
stats_update_running_avg(cc_stats_vegas_delta_drop_ma,
cwnd_diff, stats_cwnd_delta_drop_ma_count);
cwnd_diff);
cc_stats_vegas_above_delta++;
} else if (queue_use > cc->vegas_params.beta || cc->blocked_chan) {
stats_csig_blocked_ma_count++;
/* Compute the percentage we experience a blocked csig vs RTT sig */
if (cc->blocked_chan) {
cc_stats_vegas_csig_blocked_ma =
stats_update_running_avg(cc_stats_vegas_csig_blocked_ma,
100, stats_csig_blocked_ma_count);
100);
} else {
cc_stats_vegas_csig_blocked_ma =
stats_update_running_avg(cc_stats_vegas_csig_blocked_ma,
0, stats_csig_blocked_ma_count);
0);
}
cc->cwnd -= CWND_INC(cc);

30
src/lib/math/stats.h
View File

@ -10,13 +10,33 @@
#ifndef TOR_STATS_H
#define TOR_STATS_H
/** Update an average making it a "running average". The "avg" is the current
* value that will be updated to the new one. The "value" is the new value to
* add to the average and "n" is the new count as in including the "value". */
/**
* Compute an N-count EWMA, aka N-EWMA. N-EWMA is defined as:
* EWMA = alpha*value + (1-alpha)*EWMA_prev
* with alpha = 2/(N+1).
*
* This works out to:
* EWMA = value*2/(N+1) + EMA_prev*(N-1)/(N+1)
* = (value*2 + EWMA_prev*(N-1))/(N+1)
*/
static inline double
stats_update_running_avg(double avg, double value, double n)
n_count_ewma_double(double avg, double value, uint64_t N)
{
return ((avg * (n - 1)) + value) / n;
/* If the average was not previously computed, return value.
* The less than is because we have stupid C warning flags that
* prevent exact comparison to 0.0, so we can't do an exact
* check for unitialized double values. Yay pedantry!
* Love it when it introduces surprising edge case bugs like
* this will. */
if (avg < 0.0000002)
return value;
else
return (2*value + (N-1)*avg)/(N+1);
}
/* For most stats, an N_EWMA of 100 is sufficient */
#define DEFAULT_STATS_N_EWMA_COUNT 100
#define stats_update_running_avg(avg, value) \
n_count_ewma_double(avg, value, DEFAULT_STATS_N_EWMA_COUNT)
#endif /* !defined(TOR_STATS_H) */