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| author | Eric Dumazet <edumazet@google.com> | 2016-05-01 16:47:26 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2016-05-03 12:47:09 -0400 |
| commit | 9d18562a227874289fda8ca5d117d8f503f1dcca (patch) | |
| tree | c00c1688e73773f12f3071998bcf20679695dc8e /include/uapi | |
| parent | 094e43d50d7e421e9036d72a5a1d93c250cdbf0a (diff) | |
| download | linux-9d18562a227874289fda8ca5d117d8f503f1dcca.tar.bz2 | |
fq_codel: add batch ability to fq_codel_drop()
In presence of inelastic flows and stress, we can call
fq_codel_drop() for every packet entering fq_codel qdisc.
fq_codel_drop() is quite expensive, as it does a linear scan
of 4 KB of memory to find a fat flow.
Once found, it drops the oldest packet of this flow.
Instead of dropping a single packet, try to drop 50% of the backlog
of this fat flow, with a configurable limit of 64 packets per round.
TCA_FQ_CODEL_DROP_BATCH_SIZE is the new attribute to make this
limit configurable.
With this strategy the 4 KB search is amortized to a single cache line
per drop [1], so fq_codel_drop() no longer appears at the top of kernel
profile in presence of few inelastic flows.
[1] Assuming a 64byte cache line, and 1024 buckets
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Dave Taht <dave.taht@gmail.com>
Cc: Jonathan Morton <chromatix99@gmail.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Dave Taht
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/uapi')
| -rw-r--r-- | include/uapi/linux/pkt_sched.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/uapi/linux/pkt_sched.h b/include/uapi/linux/pkt_sched.h index 1c78c7454c7c..a11afecd4482 100644 --- a/include/uapi/linux/pkt_sched.h +++ b/include/uapi/linux/pkt_sched.h @@ -718,6 +718,7 @@ enum { TCA_FQ_CODEL_FLOWS, TCA_FQ_CODEL_QUANTUM, TCA_FQ_CODEL_CE_THRESHOLD, + TCA_FQ_CODEL_DROP_BATCH_SIZE, __TCA_FQ_CODEL_MAX }; |