Commit 08c3ee8e authored by Mike Perry's avatar Mike Perry Committed by David Goulet
Browse files

Create slow-start max for n_ewma_cnt. 

Since slow-start now checks every sendme, lower EWMA is better.
parent 832a1d9f

src/core/or/congestion_control_common.c

+25 −1
Original line number Diff line number Diff line
@@ -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;

}