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author | Jesper Dangaard Brouer <brouer@redhat.com> | 2019-02-19 21:53:02 +0300 |
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committer | Daniel Borkmann <daniel@iogearbox.net> | 2019-02-19 23:56:05 +0300 |
commit | 74e31ca850c1cddeca03503171dd145b6ce293b6 (patch) | |
tree | 069ba2607739490c6dcd75cb47da15b7105995b4 /samples | |
parent | 568f196756ad9fe2b49c46bbf6a9de1b190438b4 (diff) | |
download | linux-74e31ca850c1cddeca03503171dd145b6ce293b6.tar.xz |
bpf: add skb->queue_mapping write access from tc clsact
The skb->queue_mapping already have read access, via __sk_buff->queue_mapping.
This patch allow BPF tc qdisc clsact write access to the queue_mapping via
tc_cls_act_is_valid_access. Also handle that the value NO_QUEUE_MAPPING
is not allowed.
It is already possible to change this via TC filter action skbedit
tc-skbedit(8). Due to the lack of TC examples, lets show one:
# tc qdisc add dev ixgbe1 clsact
# tc filter add dev ixgbe1 ingress matchall action skbedit queue_mapping 5
# tc filter list dev ixgbe1 ingress
The most common mistake is that XPS (Transmit Packet Steering) takes
precedence over setting skb->queue_mapping. XPS is configured per DEVICE
via /sys/class/net/DEVICE/queues/tx-*/xps_cpus via a CPU hex mask. To
disable set mask=00.
The purpose of changing skb->queue_mapping is to influence the selection of
the net_device "txq" (struct netdev_queue), which influence selection of
the qdisc "root_lock" (via txq->qdisc->q.lock) and txq->_xmit_lock. When
using the MQ qdisc the txq->qdisc points to different qdiscs and associated
locks, and HARD_TX_LOCK (txq->_xmit_lock), allowing for CPU scalability.
Due to lack of TC examples, lets show howto attach clsact BPF programs:
# tc qdisc add dev ixgbe2 clsact
# tc filter add dev ixgbe2 egress bpf da obj XXX_kern.o sec tc_qmap2cpu
# tc filter list dev ixgbe2 egress
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'samples')
0 files changed, 0 insertions, 0 deletions