diff options
Diffstat (limited to 'net/dccp/ccids/lib/packet_history.c')
| -rw-r--r-- | net/dccp/ccids/lib/packet_history.c | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/net/dccp/ccids/lib/packet_history.c b/net/dccp/ccids/lib/packet_history.c index 5c4ded1..547ad09 100644 --- a/net/dccp/ccids/lib/packet_history.c +++ b/net/dccp/ccids/lib/packet_history.c @@ -385,6 +385,36 @@ int tfrc_rx_handle_loss(struct tfrc_rx_hist *h, } EXPORT_SYMBOL_GPL(tfrc_rx_handle_loss); +/* Compute the sending rate X_recv measured between feedback intervals */ +u32 tfrc_rx_hist_x_recv(struct tfrc_rx_hist *h, const u32 last_x_recv) +{ + u64 bytes = h->bytes_recvd, last_rtt = h->rtt_estimate; + s64 delta = ktime_to_us(net_timedelta(h->bytes_start)); + + WARN_ON(delta <= 0); + /* + * Ensure that the sampling interval for X_recv is at least one RTT, + * by extending the sampling interval backwards in time, over the last + * R_(m-1) seconds, as per rfc3448bis-06, 6.2. + * To reduce noise (e.g. when the RTT changes often), this is only + * done when delta is smaller than RTT/2. + */ + if (last_x_recv > 0 && delta < last_rtt/2) { + tfrc_pr_debug("delta < RTT ==> %ld us < %u us\n", + (long)delta, (unsigned)last_rtt); + + delta = (bytes ? delta : 0) + last_rtt; + bytes += div_u64((u64)last_x_recv * last_rtt, USEC_PER_SEC); + } + + if (unlikely(bytes == 0)) { + DCCP_WARN("X_recv == 0, using old value of %u\n", last_x_recv); + return last_x_recv; + } + return scaled_div32(bytes, delta); +} +EXPORT_SYMBOL_GPL(tfrc_rx_hist_x_recv); + void tfrc_rx_hist_purge(struct tfrc_rx_hist *h) { int i; |