diff options
| -rw-r--r-- | net/dccp/ccids/ccid3.c | 17 | ||||
| -rw-r--r-- | net/dccp/ccids/ccid3.h | 19 |
2 files changed, 21 insertions, 15 deletions
diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c index b4cc62e..eb1bda0 100644 --- a/net/dccp/ccids/ccid3.c +++ b/net/dccp/ccids/ccid3.c @@ -93,19 +93,16 @@ static inline u64 rfc3390_initial_rate(struct sock *sk) return scaled_div(w_init << 6, hctx->rtt); } -/* - * Recalculate t_ipi and delta (should be called whenever X changes) +/** + * ccid3_update_send_interval - Calculate new t_ipi = s / X_inst + * This respects the granularity of X_inst (64 * bytes/second). */ static void ccid3_update_send_interval(struct ccid3_hc_tx_sock *hctx) { - /* Calculate new t_ipi = s / X_inst (X_inst is in 64 * bytes/second) */ hctx->t_ipi = scaled_div32(((u64)hctx->s) << 6, hctx->x); - /* Calculate new delta by delta = min(t_ipi / 2, t_gran / 2) */ - hctx->delta = min_t(u32, hctx->t_ipi / 2, TFRC_OPSYS_HALF_TIME_GRAN); - - ccid3_pr_debug("t_ipi=%u, delta=%u, s=%u, X=%u\n", hctx->t_ipi, - hctx->delta, hctx->s, (unsigned)(hctx->x >> 6)); + ccid3_pr_debug("t_ipi=%u, s=%u, X=%u\n", hctx->t_ipi, + hctx->s, (unsigned)(hctx->x >> 6)); } static u32 ccid3_hc_tx_idle_rtt(struct ccid3_hc_tx_sock *hctx, ktime_t now) @@ -340,8 +337,8 @@ static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb) * else * // send the packet in (t_nom - t_now) milliseconds. */ - if (delay - (s64)hctx->delta >= 1000) - return (u32)delay / 1000L; + if (delay >= TFRC_T_DELTA) + return (u32)delay / USEC_PER_MSEC; ccid3_hc_tx_update_win_count(hctx, now); break; diff --git a/net/dccp/ccids/ccid3.h b/net/dccp/ccids/ccid3.h index 0cfcfff..92a5e16 100644 --- a/net/dccp/ccids/ccid3.h +++ b/net/dccp/ccids/ccid3.h @@ -47,12 +47,23 @@ /* Two seconds as per RFC 3448 4.2 */ #define TFRC_INITIAL_TIMEOUT (2 * USEC_PER_SEC) -/* In usecs - half the scheduling granularity as per RFC3448 4.6 */ -#define TFRC_OPSYS_HALF_TIME_GRAN (USEC_PER_SEC / (2 * HZ)) - /* Parameter t_mbi from [RFC 3448, 4.3]: backoff interval in seconds */ #define TFRC_T_MBI 64 +/* + * The t_delta parameter (RFC 3448, 4.6): delays of less than %USEC_PER_MSEC are + * rounded down to 0, since sk_reset_timer() here uses millisecond granularity. + * Hence we can use a constant t_delta = %USEC_PER_MSEC when HZ >= 500. A coarse + * resolution of HZ < 500 means that the error is below one timer tick (t_gran) + * when using the constant t_delta = t_gran / 2 = %USEC_PER_SEC / (2 * HZ). + */ +#if (HZ >= 500) +# define TFRC_T_DELTA USEC_PER_MSEC +#else +# define TFRC_T_DELTA (USEC_PER_SEC / (2 * HZ)) +#warning Coarse CONFIG_HZ resolution -- higher value recommended for TFRC. +#endif + enum ccid3_options { TFRC_OPT_LOSS_EVENT_RATE = 192, TFRC_OPT_LOSS_INTERVALS = 193, @@ -92,7 +103,6 @@ enum ccid3_hc_tx_states { * @no_feedback_timer - Handle to no feedback timer * @t_ld - Time last doubled during slow start * @t_nom - Nominal send time of next packet - * @delta - Send timer delta (RFC 3448, 4.6) in usecs * @hist - Packet history * @options_received - Parsed set of retrieved options */ @@ -111,7 +121,6 @@ struct ccid3_hc_tx_sock { struct timer_list no_feedback_timer; ktime_t t_ld; ktime_t t_nom; - u32 delta; struct tfrc_tx_hist_entry *hist; struct ccid3_options_received options_received; }; |
