commit a956b20c1d090ee2439f47418a6540d2f95be279 Author: Mike Perry mikeperry-git@torproject.org Date: Tue Feb 1 15:32:08 2022 +0000
Add a delta parameter to Vegas.
This allows us to cap the queue use during steady state. In shadow, this reduced instances of long circuit queues at relays. --- src/core/or/congestion_control_st.h | 2 ++ src/core/or/congestion_control_vegas.c | 28 ++++++++++++++++++++++++++-- 2 files changed, 28 insertions(+), 2 deletions(-)
diff --git a/src/core/or/congestion_control_st.h b/src/core/or/congestion_control_st.h index ea80868350..2c905772c1 100644 --- a/src/core/or/congestion_control_st.h +++ b/src/core/or/congestion_control_st.h @@ -103,6 +103,8 @@ struct vegas_params_t { uint16_t alpha; /** The queue use above which we decrement cwnd */ uint16_t beta; + /** The queue use at which we cap cwnd in steady state */ + uint16_t delta; /** Weighted average (percent) between cwnd estimator and * piecewise estimator. */ uint8_t bdp_mix_pct; diff --git a/src/core/or/congestion_control_vegas.c b/src/core/or/congestion_control_vegas.c index ff825f94cc..5c62787375 100644 --- a/src/core/or/congestion_control_vegas.c +++ b/src/core/or/congestion_control_vegas.c @@ -29,27 +29,32 @@ #define VEGAS_ALPHA_SBWS_DFLT (2*OUTBUF_CELLS-TLS_RECORD_MAX_CELLS) #define VEGAS_BETA_SBWS_DFLT (2*OUTBUF_CELLS) #define VEGAS_GAMMA_SBWS_DFLT (2*OUTBUF_CELLS) +#define VEGAS_DELTA_SBWS_DFLT (4*OUTBUF_CELLS)
/* Exits are three hops, so params are based on 3 outbufs of cells */ #define VEGAS_ALPHA_EXIT_DFLT (3*OUTBUF_CELLS-TLS_RECORD_MAX_CELLS) #define VEGAS_BETA_EXIT_DFLT (3*OUTBUF_CELLS) #define VEGAS_GAMMA_EXIT_DFLT (3*OUTBUF_CELLS) +#define VEGAS_DELTA_EXIT_DFLT (5*OUTBUF_CELLS)
/* Onion rends are six hops, so params are based on 6 outbufs of cells */ #define VEGAS_ALPHA_ONION_DFLT (6*OUTBUF_CELLS-TLS_RECORD_MAX_CELLS) #define VEGAS_BETA_ONION_DFLT (6*OUTBUF_CELLS) #define VEGAS_GAMMA_ONION_DFLT (6*OUTBUF_CELLS) +#define VEGAS_DELTA_ONION_DFLT (8*OUTBUF_CELLS)
/* Single Onions are three hops, so params are based on 3 outbufs of cells */ #define VEGAS_ALPHA_SOS_DFLT (3*OUTBUF_CELLS-TLS_RECORD_MAX_CELLS) #define VEGAS_BETA_SOS_DFLT (3*OUTBUF_CELLS) #define VEGAS_GAMMA_SOS_DFLT (3*OUTBUF_CELLS) +#define VEGAS_DELTA_SOS_DFLT (5*OUTBUF_CELLS)
/* Vanguard Onions are 7 hops (or 8 if both sides use vanguards, but that * should be rare), so params are based on 7 outbufs of cells */ #define VEGAS_ALPHA_VG_DFLT (7*OUTBUF_CELLS-TLS_RECORD_MAX_CELLS) #define VEGAS_BETA_VG_DFLT (7*OUTBUF_CELLS) #define VEGAS_GAMMA_VG_DFLT (7*OUTBUF_CELLS) +#define VEGAS_DELTA_VG_DFLT (9*OUTBUF_CELLS)
#define VEGAS_BDP_MIX_PCT 100
@@ -81,48 +86,59 @@ congestion_control_vegas_set_params(congestion_control_t *cc, { tor_assert(cc->cc_alg == CC_ALG_VEGAS); const char *alpha_str = NULL, *beta_str = NULL, *gamma_str = NULL; - int alpha, beta, gamma; + const char *delta_str = NULL; + int alpha, beta, gamma, delta;
switch (path) { case CC_PATH_SBWS: alpha_str = "cc_vegas_alpha_sbws"; beta_str = "cc_vegas_beta_sbws"; gamma_str = "cc_vegas_gamma_sbws"; + delta_str = "cc_vegas_delta_sbws"; alpha = VEGAS_ALPHA_SBWS_DFLT; beta = VEGAS_BETA_SBWS_DFLT; gamma = VEGAS_GAMMA_SBWS_DFLT; + delta = VEGAS_DELTA_SBWS_DFLT; break; case CC_PATH_EXIT: alpha_str = "cc_vegas_alpha_exit"; beta_str = "cc_vegas_beta_exit"; gamma_str = "cc_vegas_gamma_exit"; + delta_str = "cc_vegas_delta_exit"; alpha = VEGAS_ALPHA_EXIT_DFLT; beta = VEGAS_BETA_EXIT_DFLT; gamma = VEGAS_GAMMA_EXIT_DFLT; + delta = VEGAS_DELTA_EXIT_DFLT; break; case CC_PATH_ONION: alpha_str = "cc_vegas_alpha_onion"; beta_str = "cc_vegas_beta_onion"; gamma_str = "cc_vegas_gamma_onion"; + delta_str = "cc_vegas_delta_onion"; alpha = VEGAS_ALPHA_ONION_DFLT; beta = VEGAS_BETA_ONION_DFLT; gamma = VEGAS_GAMMA_ONION_DFLT; + delta = VEGAS_DELTA_ONION_DFLT; break; case CC_PATH_ONION_SOS: alpha_str = "cc_vegas_alpha_sos"; beta_str = "cc_vegas_beta_sos"; gamma_str = "cc_vegas_gamma_sos"; + delta_str = "cc_vegas_delta_sos"; alpha = VEGAS_ALPHA_SOS_DFLT; beta = VEGAS_BETA_SOS_DFLT; gamma = VEGAS_GAMMA_SOS_DFLT; + delta = VEGAS_DELTA_SOS_DFLT; break; case CC_PATH_ONION_VG: alpha_str = "cc_vegas_alpha_vg"; beta_str = "cc_vegas_beta_vg"; gamma_str = "cc_vegas_gamma_vg"; + delta_str = "cc_vegas_delta_vg"; alpha = VEGAS_ALPHA_VG_DFLT; beta = VEGAS_BETA_VG_DFLT; gamma = VEGAS_GAMMA_VG_DFLT; + delta = VEGAS_DELTA_VG_DFLT; break; default: tor_assert(0); @@ -147,6 +163,12 @@ congestion_control_vegas_set_params(congestion_control_t *cc, 0, 1000);
+ cc->vegas_params.delta = + networkstatus_get_param(NULL, delta_str, + delta, + 0, + INT32_MAX); + cc->vegas_params.bdp_mix_pct = networkstatus_get_param(NULL, "cc_vegas_bdp_mix", VEGAS_BDP_MIX_PCT, @@ -216,7 +238,9 @@ congestion_control_vegas_process_sendme(congestion_control_t *cc, log_info(LD_CIRC, "CC: TOR_VEGAS exiting slow start"); } } else { - if (queue_use > cc->vegas_params.beta || cc->blocked_chan) { + if (queue_use > cc->vegas_params.delta) { + cc->cwnd = vegas_bdp_mix(cc) + cc->vegas_params.delta - CWND_INC(cc); + } else if (queue_use > cc->vegas_params.beta || cc->blocked_chan) { cc->cwnd -= CWND_INC(cc); } else if (queue_use < cc->vegas_params.alpha) { cc->cwnd += CWND_INC(cc);