From: Gerrit Renker Date: Tue, 20 Nov 2007 20:00:39 +0000 (-0200) Subject: [CCID3]: Ignore trivial amounts of elapsed time X-Git-Tag: v2.6.25-rc1~1162^2~1368 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=eb279b79c46be767ecffadaa8ed6be3e3555e93d;p=linux-2.6 [CCID3]: Ignore trivial amounts of elapsed time This patch fixes a previously undiscovered bug; the problem is in computing the elapsed time as the time between `receiving' the packet (i.e. skb enters CCID module) and sending feedback: - there is no layer-processing, queueing, or delay involved, - hence the elapsed time is in the order of 1 function call - this is in the dimension of maximally 50..100usec - which renders the use of elapsed time almost entirely useless. The fix is simply to ignore such trivial amounts of elapsed time. As a further advantage, the now useless elapsed_time field can be removed from the socket, which reduces the socket structure by another four bytes. Signed-off-by: Gerrit Renker Signed-off-by: Ian McDonald Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: David S. Miller --- diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c index 5bf110b28a..c025236ce4 100644 --- a/net/dccp/ccids/ccid3.c +++ b/net/dccp/ccids/ccid3.c @@ -744,11 +744,6 @@ static void ccid3_hc_rx_send_feedback(struct sock *sk) hcrx->ccid3hcrx_ccval_last_counter = packet->dccphrx_ccval; hcrx->ccid3hcrx_bytes_recv = 0; - /* Elapsed time information [RFC 4340, 13.2] in units of 10 * usecs */ - delta = ktime_us_delta(now, packet->dccphrx_tstamp); - DCCP_BUG_ON(delta < 0); - hcrx->ccid3hcrx_elapsed_time = delta / 10; - if (hcrx->ccid3hcrx_p == 0) hcrx->ccid3hcrx_pinv = ~0U; /* see RFC 4342, 8.5 */ else if (hcrx->ccid3hcrx_p > 1000000) { @@ -778,10 +773,7 @@ static int ccid3_hc_rx_insert_options(struct sock *sk, struct sk_buff *skb) x_recv = htonl(hcrx->ccid3hcrx_x_recv); pinv = htonl(hcrx->ccid3hcrx_pinv); - if ((hcrx->ccid3hcrx_elapsed_time != 0 && - dccp_insert_option_elapsed_time(sk, skb, - hcrx->ccid3hcrx_elapsed_time)) || - dccp_insert_option_timestamp(sk, skb) || + if (dccp_insert_option_timestamp(sk, skb) || dccp_insert_option(sk, skb, TFRC_OPT_LOSS_EVENT_RATE, &pinv, sizeof(pinv)) || dccp_insert_option(sk, skb, TFRC_OPT_RECEIVE_RATE, diff --git a/net/dccp/ccids/ccid3.h b/net/dccp/ccids/ccid3.h index 0cdc982cfe..83467c34ed 100644 --- a/net/dccp/ccids/ccid3.h +++ b/net/dccp/ccids/ccid3.h @@ -147,7 +147,6 @@ enum ccid3_hc_rx_states { * @ccid3hcrx_li_hist - Loss Interval History * @ccid3hcrx_s - Received packet size in bytes * @ccid3hcrx_pinv - Inverse of Loss Event Rate (RFC 4342, sec. 8.5) - * @ccid3hcrx_elapsed_time - Time since packet reception */ struct ccid3_hc_rx_sock { struct tfrc_rx_info ccid3hcrx_tfrc; @@ -165,7 +164,6 @@ struct ccid3_hc_rx_sock { struct list_head ccid3hcrx_li_hist; u16 ccid3hcrx_s; u32 ccid3hcrx_pinv; - u32 ccid3hcrx_elapsed_time; }; static inline struct ccid3_hc_rx_sock *ccid3_hc_rx_sk(const struct sock *sk)