| 12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152 |
- From b8fc328668a74e1314a19266755a54abd875e5a6 Mon Sep 17 00:00:00 2001
- From: Eric Dumazet <[email protected]>
- Date: Sun, 29 Jul 2012 20:52:21 +0000
- Subject: [PATCH] codel: refine one condition to avoid a nul rec_inv_sqrt
- commit 2359a47671fc4fb0fe5e9945f76c2cb10792c0f8 upstream.
- One condition before codel_Newton_step() was not good if
- we never left the dropping state for a flow. As a result
- rec_inv_sqrt was 0, instead of the ~0 initial value.
- codel control law was then set to a very aggressive mode, dropping
- many packets before reaching 'target' and recovering from this problem.
- To keep codel_vars_init() as efficient as possible, refine
- the condition to make sure rec_inv_sqrt initial value is correct
- Many thanks to Anton Mich for discovering the issue and suggesting
- a fix.
- Reported-by: Anton Mich <[email protected]>
- Signed-off-by: Eric Dumazet <[email protected]>
- Signed-off-by: David S. Miller <[email protected]>
- ---
- include/net/codel.h | 8 ++++++--
- 1 file changed, 6 insertions(+), 2 deletions(-)
- --- a/include/net/codel.h
- +++ b/include/net/codel.h
- @@ -305,6 +305,8 @@ static struct sk_buff *codel_dequeue(str
- }
- }
- } else if (drop) {
- + u32 delta;
- +
- if (params->ecn && INET_ECN_set_ce(skb)) {
- stats->ecn_mark++;
- } else {
- @@ -320,9 +322,11 @@ static struct sk_buff *codel_dequeue(str
- * assume that the drop rate that controlled the queue on the
- * last cycle is a good starting point to control it now.
- */
- - if (codel_time_before(now - vars->drop_next,
- + delta = vars->count - vars->lastcount;
- + if (delta > 1 &&
- + codel_time_before(now - vars->drop_next,
- 16 * params->interval)) {
- - vars->count = (vars->count - vars->lastcount) | 1;
- + vars->count = delta;
- /* we dont care if rec_inv_sqrt approximation
- * is not very precise :
- * Next Newton steps will correct it quadratically.
|
