* [PATCH 0/2] dccp: fix slow slow-start by symmetric Syn-RTT [not found] <ccid3_4_tfrc_slow_slow_start_issue> @ 2010-06-22 11:14 ` Gerrit Renker 2010-06-22 11:14 ` [PATCH 1/2] dccp: remove unused function argument Gerrit Renker 2010-06-26 4:36 ` [PATCH 0/2] dccp: fix slow slow-start by symmetric Syn-RTT David Miller 0 siblings, 2 replies; 4+ messages in thread From: Gerrit Renker @ 2010-06-22 11:14 UTC (permalink / raw) To: davem; +Cc: dccp, netdev This changeset fixes slow startup behaviour for DCCP streaming via CCID-3/4 when a listening server needs to start streaming. Patch #1: removes an unused 'sk' argument from several functions, it is used by patch #2; Patch #2: fixes the sluggish slow-start problem by taking an RTT sample from the initial handshake also for listeing servers. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH 1/2] dccp: remove unused function argument 2010-06-22 11:14 ` [PATCH 0/2] dccp: fix slow slow-start by symmetric Syn-RTT Gerrit Renker @ 2010-06-22 11:14 ` Gerrit Renker 2010-06-22 11:14 ` [PATCH 2/2] dccp: make implementation of Syn-RTT symmetric Gerrit Renker 2010-06-26 4:36 ` [PATCH 0/2] dccp: fix slow slow-start by symmetric Syn-RTT David Miller 1 sibling, 1 reply; 4+ messages in thread From: Gerrit Renker @ 2010-06-22 11:14 UTC (permalink / raw) To: davem; +Cc: dccp, netdev, Gerrit Renker This removes an unused 'sk' argument from several option-inserting functions. Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk> --- net/dccp/ackvec.c | 2 +- net/dccp/ccids/ccid3.c | 4 ++-- net/dccp/dccp.h | 12 ++++-------- net/dccp/options.c | 14 ++++++-------- 4 files changed, 13 insertions(+), 19 deletions(-) --- a/net/dccp/ackvec.c +++ b/net/dccp/ackvec.c @@ -82,7 +82,7 @@ int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb) elapsed_time = delta / 10; if (elapsed_time != 0 && - dccp_insert_option_elapsed_time(sk, skb, elapsed_time)) + dccp_insert_option_elapsed_time(skb, elapsed_time)) return -1; avr = dccp_ackvec_record_new(); --- a/net/dccp/ccids/ccid3.c +++ b/net/dccp/ccids/ccid3.c @@ -715,9 +715,9 @@ static int ccid3_hc_rx_insert_options(struct sock *sk, struct sk_buff *skb) x_recv = htonl(hc->rx_x_recv); pinv = htonl(hc->rx_pinv); - if (dccp_insert_option(sk, skb, TFRC_OPT_LOSS_EVENT_RATE, + if (dccp_insert_option(skb, TFRC_OPT_LOSS_EVENT_RATE, &pinv, sizeof(pinv)) || - dccp_insert_option(sk, skb, TFRC_OPT_RECEIVE_RATE, + dccp_insert_option(skb, TFRC_OPT_RECEIVE_RATE, &x_recv, sizeof(x_recv))) return -1; --- a/net/dccp/dccp.h +++ b/net/dccp/dccp.h @@ -446,16 +446,12 @@ extern void dccp_feat_list_purge(struct list_head *fn_list); extern int dccp_insert_options(struct sock *sk, struct sk_buff *skb); extern int dccp_insert_options_rsk(struct dccp_request_sock*, struct sk_buff*); -extern int dccp_insert_option_elapsed_time(struct sock *sk, - struct sk_buff *skb, - u32 elapsed_time); +extern int dccp_insert_option_elapsed_time(struct sk_buff *skb, u32 elapsed); extern u32 dccp_timestamp(void); extern void dccp_timestamping_init(void); -extern int dccp_insert_option_timestamp(struct sock *sk, - struct sk_buff *skb); -extern int dccp_insert_option(struct sock *sk, struct sk_buff *skb, - unsigned char option, - const void *value, unsigned char len); +extern int dccp_insert_option_timestamp(struct sk_buff *skb); +extern int dccp_insert_option(struct sk_buff *skb, unsigned char option, + const void *value, unsigned char len); #ifdef CONFIG_SYSCTL extern int dccp_sysctl_init(void); --- a/net/dccp/options.c +++ b/net/dccp/options.c @@ -299,9 +299,8 @@ static inline u8 dccp_ndp_len(const u64 ndp) return likely(ndp <= USHRT_MAX) ? 2 : (ndp <= UINT_MAX ? 4 : 6); } -int dccp_insert_option(struct sock *sk, struct sk_buff *skb, - const unsigned char option, - const void *value, const unsigned char len) +int dccp_insert_option(struct sk_buff *skb, const unsigned char option, + const void *value, const unsigned char len) { unsigned char *to; @@ -354,8 +353,7 @@ static inline int dccp_elapsed_time_len(const u32 elapsed_time) return elapsed_time == 0 ? 0 : elapsed_time <= 0xFFFF ? 2 : 4; } -int dccp_insert_option_elapsed_time(struct sock *sk, struct sk_buff *skb, - u32 elapsed_time) +int dccp_insert_option_elapsed_time(struct sk_buff *skb, u32 elapsed_time) { const int elapsed_time_len = dccp_elapsed_time_len(elapsed_time); const int len = 2 + elapsed_time_len; @@ -386,13 +384,13 @@ int dccp_insert_option_elapsed_time(struct sock *sk, struct sk_buff *skb, EXPORT_SYMBOL_GPL(dccp_insert_option_elapsed_time); -int dccp_insert_option_timestamp(struct sock *sk, struct sk_buff *skb) +int dccp_insert_option_timestamp(struct sk_buff *skb) { __be32 now = htonl(dccp_timestamp()); /* yes this will overflow but that is the point as we want a * 10 usec 32 bit timer which mean it wraps every 11.9 hours */ - return dccp_insert_option(sk, skb, DCCPO_TIMESTAMP, &now, sizeof(now)); + return dccp_insert_option(skb, DCCPO_TIMESTAMP, &now, sizeof(now)); } EXPORT_SYMBOL_GPL(dccp_insert_option_timestamp); @@ -533,7 +531,7 @@ int dccp_insert_options(struct sock *sk, struct sk_buff *skb) * Obtain RTT sample from Request/Response exchange. * This is currently used in CCID 3 initialisation. */ - if (dccp_insert_option_timestamp(sk, skb)) + if (dccp_insert_option_timestamp(skb)) return -1; } else if (dp->dccps_hc_rx_ackvec != NULL && -- 1.6.0.rc2 ^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH 2/2] dccp: make implementation of Syn-RTT symmetric 2010-06-22 11:14 ` [PATCH 1/2] dccp: remove unused function argument Gerrit Renker @ 2010-06-22 11:14 ` Gerrit Renker 0 siblings, 0 replies; 4+ messages in thread From: Gerrit Renker @ 2010-06-22 11:14 UTC (permalink / raw) To: davem; +Cc: dccp, netdev, Gerrit Renker This patch is thanks to Andre Noll who reported the issue and helped testing. The Syn-RTT sampled during the initial handshake currently only works for the client sending the DCCP-Request. TFRC penalizes the absence of an RTT sample with a very slow initial speed (1 packet per second), which delays slow-start significantly, resulting in sluggish performance. This patch mirrors the "Syn RTT" principle by adding a timestamp also onto the DCCP-Response, producing an RTT sample when the (Data)Ack completing the handshake arrives. Also changed the documentation to 'TFRC' since Syn RTTs are also used by CCID-4. Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk> --- net/dccp/input.c | 13 +++++++++++-- net/dccp/options.c | 6 +++++- 2 files changed, 16 insertions(+), 3 deletions(-) --- a/net/dccp/input.c +++ b/net/dccp/input.c @@ -430,7 +430,7 @@ static int dccp_rcv_request_sent_state_process(struct sock *sk, if (dccp_parse_options(sk, NULL, skb)) return 1; - /* Obtain usec RTT sample from SYN exchange (used by CCID 3) */ + /* Obtain usec RTT sample from SYN exchange (used by TFRC). */ if (likely(dp->dccps_options_received.dccpor_timestamp_echo)) dp->dccps_syn_rtt = dccp_sample_rtt(sk, 10 * (tstamp - dp->dccps_options_received.dccpor_timestamp_echo)); @@ -535,6 +535,8 @@ static int dccp_rcv_respond_partopen_state_process(struct sock *sk, const struct dccp_hdr *dh, const unsigned len) { + struct dccp_sock *dp = dccp_sk(sk); + u32 sample = dp->dccps_options_received.dccpor_timestamp_echo; int queued = 0; switch (dh->dccph_type) { @@ -559,7 +561,14 @@ static int dccp_rcv_respond_partopen_state_process(struct sock *sk, if (sk->sk_state == DCCP_PARTOPEN) inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); - dccp_sk(sk)->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq; + /* Obtain usec RTT sample from SYN exchange (used by TFRC). */ + if (likely(sample)) { + long delta = dccp_timestamp() - sample; + + dp->dccps_syn_rtt = dccp_sample_rtt(sk, 10 * delta); + } + + dp->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq; dccp_set_state(sk, DCCP_OPEN); if (dh->dccph_type == DCCP_PKT_DATAACK || --- a/net/dccp/options.c +++ b/net/dccp/options.c @@ -529,7 +529,7 @@ int dccp_insert_options(struct sock *sk, struct sk_buff *skb) if (DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_REQUEST) { /* * Obtain RTT sample from Request/Response exchange. - * This is currently used in CCID 3 initialisation. + * This is currently used for TFRC initialisation. */ if (dccp_insert_option_timestamp(skb)) return -1; @@ -562,6 +562,10 @@ int dccp_insert_options_rsk(struct dccp_request_sock *dreq, struct sk_buff *skb) if (dccp_feat_insert_opts(NULL, dreq, skb)) return -1; + /* Obtain RTT sample from Response/Ack exchange (used by TFRC). */ + if (dccp_insert_option_timestamp(skb)) + return -1; + if (dreq->dreq_timestamp_echo != 0 && dccp_insert_option_timestamp_echo(NULL, dreq, skb)) return -1; -- 1.6.0.rc2 ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH 0/2] dccp: fix slow slow-start by symmetric Syn-RTT 2010-06-22 11:14 ` [PATCH 0/2] dccp: fix slow slow-start by symmetric Syn-RTT Gerrit Renker 2010-06-22 11:14 ` [PATCH 1/2] dccp: remove unused function argument Gerrit Renker @ 2010-06-26 4:36 ` David Miller 1 sibling, 0 replies; 4+ messages in thread From: David Miller @ 2010-06-26 4:36 UTC (permalink / raw) To: gerrit; +Cc: dccp, netdev From: Gerrit Renker <gerrit@erg.abdn.ac.uk> Date: Tue, 22 Jun 2010 13:14:33 +0200 > This changeset fixes slow startup behaviour for DCCP streaming via > CCID-3/4 when a listening server needs to start streaming. > > Patch #1: removes an unused 'sk' argument from several functions, > it is used by patch #2; > > Patch #2: fixes the sluggish slow-start problem by taking an RTT > sample from the initial handshake also for listeing servers. Both applied to net-next-2.6, thanks! ^ permalink raw reply [flat|nested] 4+ messages in thread
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[not found] <ccid3_4_tfrc_slow_slow_start_issue>
2010-06-22 11:14 ` [PATCH 0/2] dccp: fix slow slow-start by symmetric Syn-RTT Gerrit Renker
2010-06-22 11:14 ` [PATCH 1/2] dccp: remove unused function argument Gerrit Renker
2010-06-22 11:14 ` [PATCH 2/2] dccp: make implementation of Syn-RTT symmetric Gerrit Renker
2010-06-26 4:36 ` [PATCH 0/2] dccp: fix slow slow-start by symmetric Syn-RTT David Miller
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