[54/74] tcp: preserve ACK clocking in TSO
3.2.43-rc1 review patch. If anyone has any objections, please let me know. -- From: Eric Dumazet [ Upstream commit f4541d60a449afd40448b06496dcd510f505928e ] A long standing problem with TSO is the fact that tcp_tso_should_defer() rearms the deferred timer, while it should not. Current code leads to following bad bursty behavior : 20:11:24.484333 IP A > B: . 297161:316921(19760) ack 1 win 119 20:11:24.484337 IP B > A: . ack 263721 win 1117 20:11:24.485086 IP B > A: . ack 265241 win 1117 20:11:24.485925 IP B > A: . ack 266761 win 1117 20:11:24.486759 IP B > A: . ack 268281 win 1117 20:11:24.487594 IP B > A: . ack 269801 win 1117 20:11:24.488430 IP B > A: . ack 271321 win 1117 20:11:24.489267 IP B > A: . ack 272841 win 1117 20:11:24.490104 IP B > A: . ack 274361 win 1117 20:11:24.490939 IP B > A: . ack 275881 win 1117 20:11:24.491775 IP B > A: . ack 277401 win 1117 20:11:24.491784 IP A > B: . 316921:332881(15960) ack 1 win 119 20:11:24.492620 IP B > A: . ack 278921 win 1117 20:11:24.493448 IP B > A: . ack 280441 win 1117 20:11:24.494286 IP B > A: . ack 281961 win 1117 20:11:24.495122 IP B > A: . ack 283481 win 1117 20:11:24.495958 IP B > A: . ack 285001 win 1117 20:11:24.496791 IP B > A: . ack 286521 win 1117 20:11:24.497628 IP B > A: . ack 288041 win 1117 20:11:24.498459 IP B > A: . ack 289561 win 1117 20:11:24.499296 IP B > A: . ack 291081 win 1117 20:11:24.500133 IP B > A: . ack 292601 win 1117 20:11:24.500970 IP B > A: . ack 294121 win 1117 20:11:24.501388 IP B > A: . ack 295641 win 1117 20:11:24.501398 IP A > B: . 332881:351881(19000) ack 1 win 119 While the expected behavior is more like : 20:19:49.259620 IP A > B: . 197601:202161(4560) ack 1 win 119 20:19:49.260446 IP B > A: . ack 154281 win 1212 20:19:49.261282 IP B > A: . ack 155801 win 1212 20:19:49.262125 IP B > A: . ack 157321 win 1212 20:19:49.262136 IP A > B: . 202161:206721(4560) ack 1 win 119 20:19:49.262958 IP B > A: . ack 158841 win 1212 20:19:49.263795 IP B > A: . ack 160361 win 1212 20:19:49.264628 IP B > A: . ack 161881 win 1212 20:19:49.264637 IP A > B: . 206721:211281(4560) ack 1 win 119 20:19:49.265465 IP B > A: . ack 163401 win 1212 20:19:49.265886 IP B > A: . ack 164921 win 1212 20:19:49.266722 IP B > A: . ack 166441 win 1212 20:19:49.266732 IP A > B: . 211281:215841(4560) ack 1 win 119 20:19:49.267559 IP B > A: . ack 167961 win 1212 20:19:49.268394 IP B > A: . ack 169481 win 1212 20:19:49.269232 IP B > A: . ack 171001 win 1212 20:19:49.269241 IP A > B: . 215841:221161(5320) ack 1 win 119 Signed-off-by: Eric Dumazet Cc: Yuchung Cheng Cc: Van Jacobson Cc: Neal Cardwell Cc: Nandita Dukkipati Signed-off-by: David S. Miller Signed-off-by: Ben Hutchings --- net/ipv4/tcp_output.c | 7 +-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 9bb7400..5c1807c 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -1587,8 +1587,11 @@ static int tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb) goto send_now; } - /* Ok, it looks like it is advisable to defer. */ - tp->tso_deferred = 1 | (jiffies << 1); + /* Ok, it looks like it is advisable to defer. +* Do not rearm the timer if already set to not break TCP ACK clocking. +*/ + if (!tp->tso_deferred) + tp->tso_deferred = 1 | (jiffies << 1); return 1; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[54/74] tcp: preserve ACK clocking in TSO
3.2.43-rc1 review patch. If anyone has any objections, please let me know. -- From: Eric Dumazet eduma...@google.com [ Upstream commit f4541d60a449afd40448b06496dcd510f505928e ] A long standing problem with TSO is the fact that tcp_tso_should_defer() rearms the deferred timer, while it should not. Current code leads to following bad bursty behavior : 20:11:24.484333 IP A B: . 297161:316921(19760) ack 1 win 119 20:11:24.484337 IP B A: . ack 263721 win 1117 20:11:24.485086 IP B A: . ack 265241 win 1117 20:11:24.485925 IP B A: . ack 266761 win 1117 20:11:24.486759 IP B A: . ack 268281 win 1117 20:11:24.487594 IP B A: . ack 269801 win 1117 20:11:24.488430 IP B A: . ack 271321 win 1117 20:11:24.489267 IP B A: . ack 272841 win 1117 20:11:24.490104 IP B A: . ack 274361 win 1117 20:11:24.490939 IP B A: . ack 275881 win 1117 20:11:24.491775 IP B A: . ack 277401 win 1117 20:11:24.491784 IP A B: . 316921:332881(15960) ack 1 win 119 20:11:24.492620 IP B A: . ack 278921 win 1117 20:11:24.493448 IP B A: . ack 280441 win 1117 20:11:24.494286 IP B A: . ack 281961 win 1117 20:11:24.495122 IP B A: . ack 283481 win 1117 20:11:24.495958 IP B A: . ack 285001 win 1117 20:11:24.496791 IP B A: . ack 286521 win 1117 20:11:24.497628 IP B A: . ack 288041 win 1117 20:11:24.498459 IP B A: . ack 289561 win 1117 20:11:24.499296 IP B A: . ack 291081 win 1117 20:11:24.500133 IP B A: . ack 292601 win 1117 20:11:24.500970 IP B A: . ack 294121 win 1117 20:11:24.501388 IP B A: . ack 295641 win 1117 20:11:24.501398 IP A B: . 332881:351881(19000) ack 1 win 119 While the expected behavior is more like : 20:19:49.259620 IP A B: . 197601:202161(4560) ack 1 win 119 20:19:49.260446 IP B A: . ack 154281 win 1212 20:19:49.261282 IP B A: . ack 155801 win 1212 20:19:49.262125 IP B A: . ack 157321 win 1212 20:19:49.262136 IP A B: . 202161:206721(4560) ack 1 win 119 20:19:49.262958 IP B A: . ack 158841 win 1212 20:19:49.263795 IP B A: . ack 160361 win 1212 20:19:49.264628 IP B A: . ack 161881 win 1212 20:19:49.264637 IP A B: . 206721:211281(4560) ack 1 win 119 20:19:49.265465 IP B A: . ack 163401 win 1212 20:19:49.265886 IP B A: . ack 164921 win 1212 20:19:49.266722 IP B A: . ack 166441 win 1212 20:19:49.266732 IP A B: . 211281:215841(4560) ack 1 win 119 20:19:49.267559 IP B A: . ack 167961 win 1212 20:19:49.268394 IP B A: . ack 169481 win 1212 20:19:49.269232 IP B A: . ack 171001 win 1212 20:19:49.269241 IP A B: . 215841:221161(5320) ack 1 win 119 Signed-off-by: Eric Dumazet eduma...@google.com Cc: Yuchung Cheng ych...@google.com Cc: Van Jacobson v...@google.com Cc: Neal Cardwell ncardw...@google.com Cc: Nandita Dukkipati nandi...@google.com Signed-off-by: David S. Miller da...@davemloft.net Signed-off-by: Ben Hutchings b...@decadent.org.uk --- net/ipv4/tcp_output.c | 7 +-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 9bb7400..5c1807c 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -1587,8 +1587,11 @@ static int tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb) goto send_now; } - /* Ok, it looks like it is advisable to defer. */ - tp-tso_deferred = 1 | (jiffies 1); + /* Ok, it looks like it is advisable to defer. +* Do not rearm the timer if already set to not break TCP ACK clocking. +*/ + if (!tp-tso_deferred) + tp-tso_deferred = 1 | (jiffies 1); return 1; -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
