From ee3f1c93841bd6d0fd57996461ede727fe53d206 Mon Sep 17 00:00:00 2001 From: Ben Hutchings Date: Sat, 29 Sep 2012 12:20:38 +0000 Subject: [PATCH] codel: refine one condition to avoid a nul rec_inv_sqrt svn path=/dists/sid/linux/; revision=19403 --- debian/changelog | 6 +++ ...-condition-to-avoid-a-nul-rec_inv_sq.patch | 53 +++++++++++++++++++ debian/patches/series | 1 + 3 files changed, 60 insertions(+) create mode 100644 debian/patches/features/all/codel/0008-codel-refine-one-condition-to-avoid-a-nul-rec_inv_sq.patch diff --git a/debian/changelog b/debian/changelog index 66cef166f..2f33c7532 100644 --- a/debian/changelog +++ b/debian/changelog @@ -1,3 +1,9 @@ +linux (3.2.30-2) UNRELEASED; urgency=low + + * codel: refine one condition to avoid a nul rec_inv_sqrt + + -- Ben Hutchings Sat, 29 Sep 2012 14:19:46 +0200 + linux (3.2.30-1) unstable; urgency=low * New upstream stable update: diff --git a/debian/patches/features/all/codel/0008-codel-refine-one-condition-to-avoid-a-nul-rec_inv_sq.patch b/debian/patches/features/all/codel/0008-codel-refine-one-condition-to-avoid-a-nul-rec_inv_sq.patch new file mode 100644 index 000000000..fc43774c4 --- /dev/null +++ b/debian/patches/features/all/codel/0008-codel-refine-one-condition-to-avoid-a-nul-rec_inv_sq.patch @@ -0,0 +1,53 @@ +From: Eric Dumazet +Date: Sun, 29 Jul 2012 20:52:21 +0000 +Subject: 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 +Signed-off-by: Eric Dumazet +Signed-off-by: David S. Miller +--- + include/net/codel.h | 8 ++++++-- + 1 file changed, 6 insertions(+), 2 deletions(-) + +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. diff --git a/debian/patches/series b/debian/patches/series index 0dd72f3a3..e69b6aa42 100644 --- a/debian/patches/series +++ b/debian/patches/series @@ -271,6 +271,7 @@ features/all/codel/0004-net-codel-Add-missing-include-linux-prefetch.h.patch features/all/codel/0005-net-codel-fix-build-errors.patch features/all/codel/0006-codel-use-u16-field-instead-of-31bits-for-rec_inv_sq.patch features/all/codel/0007-fq_codel-should-use-qdisc-backlog-as-threshold.patch +features/all/codel/0008-codel-refine-one-condition-to-avoid-a-nul-rec_inv_sq.patch # AppArmor userland compatibility. This had better be gone in wheezy+1! features/all/AppArmor-compatibility-patch-for-v5-interface.patch