diff options
| -rw-r--r-- | target/linux/generic/patches-3.3/049-codel-refine-one-condition-to-avoid-a-nul-rec_inv_sqrt.patch | 68 |
1 files changed, 68 insertions, 0 deletions
diff --git a/target/linux/generic/patches-3.3/049-codel-refine-one-condition-to-avoid-a-nul-rec_inv_sqrt.patch b/target/linux/generic/patches-3.3/049-codel-refine-one-condition-to-avoid-a-nul-rec_inv_sqrt.patch new file mode 100644 index 0000000000..210a58c6a7 --- /dev/null +++ b/target/linux/generic/patches-3.3/049-codel-refine-one-condition-to-avoid-a-nul-rec_inv_sqrt.patch @@ -0,0 +1,68 @@ +From patchwork Mon Jul 30 06:52:21 2012 +Content-Type: text/plain; charset="utf-8" +MIME-Version: 1.0 +Content-Transfer-Encoding: 7bit +Subject: codel: refine one condition to avoid a nul rec_inv_sqrt +Date: Sun, 29 Jul 2012 20:52:21 -0000 +From: Eric Dumazet <eric.dumazet@gmail.com> +X-Patchwork-Id: 173968 +Message-Id: <1343631141.2626.13293.camel@edumazet-glaptop> +To: David Miller <davem@davemloft.net> +Cc: netdev <netdev@vger.kernel.org>, Anton Mich <lp2s1h@gmail.com> + +From: Eric Dumazet <edumazet@google.com> + +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 <lp2s1h@gmail.com> +Signed-off-by: Eric Dumazet <edumazet@google.com> + +--- +include/net/codel.h | 8 ++++++-- + 1 file changed, 6 insertions(+), 2 deletions(-) + + + +-- +To unsubscribe from this list: send the line "unsubscribe netdev" in +the body of a message to majordomo@vger.kernel.org +More majordomo info at http://vger.kernel.org/majordomo-info.html + +diff --git a/include/net/codel.h b/include/net/codel.h +index 550debf..389cf62 100644 +--- a/include/net/codel.h ++++ b/include/net/codel.h +@@ -305,6 +305,8 @@ static struct sk_buff *codel_dequeue(struct Qdisc *sch, + } + } + } 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(struct Qdisc *sch, + * 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. |