On Sun, 2012-06-24 at 22:00 -0700, Dave Täht wrote: > From: Dave Taht <[email protected]> > > ECN was not part of the original codel design and adding support > for it revealed problems in two areas. 1) ECN can be gamed. > 2) Dropping packets under overload more rapidly frees up > bandwidth than marking packets. > > Two possible scenarios of use - on egress from a network, > ecn_target could be set low, to drop more often, to > ensure lowest latency for other packets. > > On ingress, it could be set high to mark packets more often, > to lower data loss while still signalling the end application > that bandwidth is a problem. > > ecn_target is not engaged until after codel enters a dropping > state overall. > --- > include/linux/pkt_sched.h | 2 ++ > man/man8/tc-codel.8 | 3 +++ > man/man8/tc-fq_codel.8 | 5 +++++ > tc/q_codel.c | 17 ++++++++++++++++- > tc/q_fq_codel.c | 17 ++++++++++++++++- > 5 files changed, 42 insertions(+), 2 deletions(-) > > diff --git a/include/linux/pkt_sched.h b/include/linux/pkt_sched.h > index 32aef0a..f0dcf8c 100644 > --- a/include/linux/pkt_sched.h > +++ b/include/linux/pkt_sched.h > @@ -663,6 +663,7 @@ enum { > TCA_CODEL_LIMIT, > TCA_CODEL_INTERVAL, > TCA_CODEL_ECN, > + TCA_CODEL_ECN_TARGET, > __TCA_CODEL_MAX > }; > > @@ -691,6 +692,7 @@ enum { > TCA_FQ_CODEL_ECN, > TCA_FQ_CODEL_FLOWS, > TCA_FQ_CODEL_QUANTUM, > + TCA_FQ_CODEL_ECN_TARGET, > __TCA_FQ_CODEL_MAX > }; > > diff --git a/man/man8/tc-codel.8 b/man/man8/tc-codel.8 > index 61f163f..0e97249 100644 > --- a/man/man8/tc-codel.8 > +++ b/man/man8/tc-codel.8 > @@ -64,6 +64,9 @@ is the acceptable minimum standing/persistent queue delay. > This minimum delay > is identified by tracking the local minimum queue delay that packets > experience. > Default and recommended value is 5ms. > > +.SS ecn_target > +is the overall delay at which ecn marked packets will be dropped rather than > marked. > + > .SS interval > is used to ensure that the measured minimum delay does not become too stale. > The > minimum delay must be experienced in the last epoch of length > diff --git a/man/man8/tc-fq_codel.8 b/man/man8/tc-fq_codel.8 > index 8b43c10..9cb5be8 100644 > --- a/man/man8/tc-fq_codel.8 > +++ b/man/man8/tc-fq_codel.8 > @@ -49,6 +49,11 @@ and is the acceptable minimum > standing/persistent queue delay. This minimum delay is identified by tracking > the local minimum queue delay that packets experience. Default value is 5ms. > > +.SS ecn_target > +has the same semantics as > +.B codel > +and is the delay beyond which ecn packets will be dropped rather than marked. > +
What do you mean by "ecn_target has the same semantics as codel" ? _______________________________________________ Codel mailing list [email protected] https://lists.bufferbloat.net/listinfo/codel
