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commit 08c3ee8eca4bf60f3218daeb65acf97da554e80f Author: Mike Perry mikeperry-git@torproject.org AuthorDate: Sun Jul 31 16:38:34 2022 +0000
Create slow-start max for n_ewma_cnt.
Since slow-start now checks every sendme, lower EWMA is better. --- src/core/or/congestion_control_common.c | 26 +++++++++++++++++++++++++- 1 file changed, 25 insertions(+), 1 deletion(-)
diff --git a/src/core/or/congestion_control_common.c b/src/core/or/congestion_control_common.c index 8f09a80bae..c1a62cada0 100644 --- a/src/core/or/congestion_control_common.c +++ b/src/core/or/congestion_control_common.c @@ -52,6 +52,7 @@
#define N_EWMA_CWND_PCT_DFLT (50) #define N_EWMA_MAX_DFLT (10) +#define N_EWMA_SS_DFLT (2)
/* BDP algorithms for each congestion control algorithms use the piecewise * estimattor. See section 3.1.4 of proposal 324. */ @@ -107,6 +108,11 @@ static uint8_t n_ewma_cwnd_pct; */ static uint8_t n_ewma_max;
+/** + * Maximum number N for the N-count EWMA averaging of RTT in Slow Start. + */ +static uint8_t n_ewma_ss; + /** * Minimum number of sendmes before we begin BDP estimates */ @@ -196,6 +202,14 @@ congestion_control_new_consensus_params(const networkstatus_t *ns) N_EWMA_MAX_DFLT, N_EWMA_MAX_MIN, N_EWMA_MAX_MAX); + +#define N_EWMA_SS_MIN 2 +#define N_EWMA_SS_MAX (INT32_MAX) + n_ewma_ss = + networkstatus_get_param(NULL, "cc_ewma_ss", + N_EWMA_SS_DFLT, + N_EWMA_SS_MIN, + N_EWMA_SS_MAX); }
/** @@ -452,8 +466,18 @@ dequeue_timestamp(smartlist_t *timestamps_u64_usecs) static inline uint64_t n_ewma_count(const congestion_control_t *cc) { - uint64_t ewma_cnt = MIN(CWND_UPDATE_RATE(cc)*n_ewma_cwnd_pct/100, + uint64_t ewma_cnt = 0; + + if (cc->in_slow_start) { + /* In slow-start, we check the Vegas condition every sendme, + * so much lower ewma counts are needed. */ + ewma_cnt = n_ewma_ss; + } else { + /* After slow-start, we check the Vegas condition only once per + * CWND, so it is better to average over longer periods. */ + ewma_cnt = MIN(CWND_UPDATE_RATE(cc)*n_ewma_cwnd_pct/100, n_ewma_max); + } ewma_cnt = MAX(ewma_cnt, 2); return ewma_cnt; }