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2016-06-25net_sched: drop packets after root qdisc lock is releasedEric Dumazet1-5/+5
Qdisc performance suffers when packets are dropped at enqueue() time because drops (kfree_skb()) are done while qdisc lock is held, delaying a dequeue() draining the queue. Nominal throughput can be reduced by 50 % when this happens, at a time we would like the dequeue() to proceed as fast as possible. Even FQ is vulnerable to this problem, while one of FQ goals was to provide some flow isolation. This patch adds a 'struct sk_buff **to_free' parameter to all qdisc->enqueue(), and in qdisc_drop() helper. I measured a performance increase of up to 12 %, but this patch is a prereq so that future batches in enqueue() can fly. Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-06-15net_sched: sch_hhf: defer skb freeingEric Dumazet1-2/+2
Both hhf_reset() and hhf_change() can use rtnl_kfree_skbs() Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-06-08sched: remove qdisc->dropFlorian Westphal1-10/+0
after removal of TCA_CBQ_OVL_STRATEGY from cbq scheduler, there are no more callers of ->drop() outside of other ->drop functions, i.e. nothing calls them. Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-02-29net_sched: update hierarchical backlog tooWANG Cong1-3/+7
When the bottom qdisc decides to, for example, drop some packet, it calls qdisc_tree_decrease_qlen() to update the queue length for all its ancestors, we need to update the backlog too to keep the stats on root qdisc accurate. Cc: Jamal Hadi Salim <jhs@mojatatu.com> Acked-by: Jamal Hadi Salim <jhs@mojatatu.com> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-10-11sch_hhf: fix return value of hhf_drop()WANG Cong1-1/+10
Similar to commit c0afd9ce4d6a ("fq_codel: fix return value of fq_codel_drop()") ->drop() is supposed to return the number of bytes it dropped, but hhf_drop () returns the id of the bucket where it drops a packet from. Cc: Jamal Hadi Salim <jhs@mojatatu.com> Cc: Terry Lam <vtlam@google.com> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> Signed-off-by: Cong Wang <cwang@twopensource.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-05-04sched: Call skb_get_hash_perturb in sch_hhfTom Herbert1-18/+1
Call skb_get_hash_perturb instead of doing skb_flow_dissect and then jhash by hand. Signed-off-by: Tom Herbert <tom@herbertland.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-09-30net: sched: implement qstat helper routinesJohn Fastabend1-4/+4
This adds helpers to manipulate qstats logic and replaces locations that touch the counters directly. This simplifies future patches to push qstats onto per cpu counters. Signed-off-by: John Fastabend <john.r.fastabend@intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-06-05net: use the new API kvfree()WANG Cong1-6/+1
It is available since v3.15-rc5. Cc: Pablo Neira Ayuso <pablo@netfilter.org> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-05-12sch_hhf: fix comparison of qlen and limitYang Yingliang1-1/+1
When I use the following command, eth0 cannot send any packets. #tc qdisc add dev eth0 root handle 1: hhf limit 1 Because qlen need be smaller than limit, all packets were dropped. Fix this by qlen *<=* limit. Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-05-04net: sched: lock imbalance in hhf qdiscJohn Fastabend1-5/+6
hhf_change() takes the sch_tree_lock and releases it but misses the error cases. Fix the missed case here. To reproduce try a command like this, # tc qdisc change dev p3p2 root hhf quantum 40960 non_hh_weight 300000 Signed-off-by: John Fastabend <john.r.fastabend@intel.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-03-13net_sched: return nla_nest_end() instead of skb->lenYang Yingliang1-2/+1
nla_nest_end() already has return skb->len, so replace return skb->len with return nla_nest_end instead(). Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-01-14net: replace macros net_random and net_srandom with direct calls to prandomAruna-Hewapathirane1-1/+1
This patch removes the net_random and net_srandom macros and replaces them with direct calls to the prandom ones. As new commits only seem to use prandom_u32 there is no use to keep them around. This change makes it easier to grep for users of prandom_u32. Signed-off-by: Aruna-Hewapathirane <aruna.hewapathirane@gmail.com> Suggested-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-01-13HHF qdisc: fix jiffies-time conversion.Terry Lam1-6/+6
This is to be compatible with the use of "get_time" (i.e. default time unit in us) in iproute2 patch for HHF as requested by Stephen. Signed-off-by: Terry Lam <vtlam@google.com> Acked-by: Nandita Dukkipati <nanditad@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-12-26hhf: make qdisc ops staticstephen hemminger1-2/+1
This module shouldn't be randomly exporting symbols Signed-off-by: Stephen Hemminger <stephen@networkplumber.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-12-19net-qdisc-hhf: Heavy-Hitter Filter (HHF) qdiscTerry Lam1-0/+746
This patch implements the first size-based qdisc that attempts to differentiate between small flows and heavy-hitters. The goal is to catch the heavy-hitters and move them to a separate queue with less priority so that bulk traffic does not affect the latency of critical traffic. Currently "less priority" means less weight (2:1 in particular) in a Weighted Deficit Round Robin (WDRR) scheduler. In essence, this patch addresses the "delay-bloat" problem due to bloated buffers. In some systems, large queues may be necessary for obtaining CPU efficiency, or due to the presence of unresponsive traffic like UDP, or just a large number of connections with each having a small amount of outstanding traffic. In these circumstances, HHF aims to reduce the HoL blocking for latency sensitive traffic, while not impacting the queues built up by bulk traffic. HHF can also be used in conjunction with other AQM mechanisms such as CoDel. To capture heavy-hitters, we implement the "multi-stage filter" design in the following paper: C. Estan and G. Varghese, "New Directions in Traffic Measurement and Accounting", in ACM SIGCOMM, 2002. Some configurable qdisc settings through 'tc': - hhf_reset_timeout: period to reset counter values in the multi-stage filter (default 40ms) - hhf_admit_bytes: threshold to classify heavy-hitters (default 128KB) - hhf_evict_timeout: threshold to evict idle heavy-hitters (default 1s) - hhf_non_hh_weight: Weighted Deficit Round Robin (WDRR) weight for non-heavy-hitters (default 2) - hh_flows_limit: max number of heavy-hitter flow entries (default 2048) Note that the ratio between hhf_admit_bytes and hhf_reset_timeout reflects the bandwidth of heavy-hitters that we attempt to capture (25Mbps with the above default settings). The false negative rate (heavy-hitter flows getting away unclassified) is zero by the design of the multi-stage filter algorithm. With 100 heavy-hitter flows, using four hashes and 4000 counters yields a false positive rate (non-heavy-hitters mistakenly classified as heavy-hitters) of less than 1e-4. Signed-off-by: Terry Lam <vtlam@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>