linux-stable.git/net/sched, branch v3.9

pkt_sched: fix error return code in fw_change_attrs()

2013-04-19T21:34:53+00:00

Fix to return -EINVAL when tb[TCA_FW_MASK] is set and head->mask != 0xFFFFFFFF
instead of 0 (ifdef CONFIG_NET_CLS_IND and tb[TCA_FW_INDEV]), as done elsewhere
in this function.

Signed-off-by: Wei Yongjun 
Signed-off-by: Jamal Hadi Salim 
Signed-off-by: David S. Miller

cbq: incorrect processing of high limits

2013-04-02T18:29:20+00:00

currently cbq works incorrectly for limits > 10% real link bandwidth,
and practically does not work for limits > 50% real link bandwidth.
Below are results of experiments taken on 1 Gbit link

 In shaper | Actual Result
-----------+---------------
  100M     | 108 Mbps
  200M     | 244 Mbps
  300M     | 412 Mbps
  500M     | 893 Mbps

This happen because of q->now changes incorrectly in cbq_dequeue():
when it is called before real end of packet transmitting,
L2T is greater than real time delay, q_now gets an extra boost
but never compensate it.

To fix this problem we prevent change of q->now until its synchronization
with real time.

Signed-off-by: Vasily Averin 
Reviewed-by: Alexey Kuznetsov 
Acked-by: Eric Dumazet 
Signed-off-by: David S. Miller

net: fq_codel: Fix off-by-one error

2013-03-29T19:32:23+00:00

Currently, we hold a max of sch->limit -1 number of packets instead of
sch->limit packets. Fix this off-by-one error.

Signed-off-by: Vijay Subramanian 
Acked-by: Eric Dumazet 
Signed-off-by: David S. Miller

sch: add missing u64 in psched_ratecfg_precompute()

2013-03-27T18:06:41+00:00

It seems that commit

commit 292f1c7ff6cc10516076ceeea45ed11833bb71c7
Author: Jiri Pirko 
Date:   Tue Feb 12 00:12:03 2013 +0000

    sch: make htb_rate_cfg and functions around that generic

adds little regression.

Before:

# tc qdisc add dev eth0 root handle 1: htb default ffff
# tc class add dev eth0 classid 1:ffff htb rate 5Gbit
# tc -s class show dev eth0
class htb 1:ffff root prio 0 rate 5000Mbit ceil 5000Mbit burst 625b cburst
625b
 Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
 rate 0bit 0pps backlog 0b 0p requeues 0
 lended: 0 borrowed: 0 giants: 0
 tokens: 31 ctokens: 31

After:

# tc qdisc add dev eth0 root handle 1: htb default ffff
# tc class add dev eth0 classid 1:ffff htb rate 5Gbit
# tc -s class show dev eth0
class htb 1:ffff root prio 0 rate 1544Mbit ceil 1544Mbit burst 625b cburst
625b
 Sent 5073 bytes 41 pkt (dropped 0, overlimits 0 requeues 0)
 rate 1976bit 2pps backlog 0b 0p requeues 0
 lended: 41 borrowed: 0 giants: 0
 tokens: 1802 ctokens: 1802

This probably due to lost u64 cast of rate parameter in
psched_ratecfg_precompute() (net/sched/sch_generic.c).

Signed-off-by: Sergey Popovich 
Acked-by: Eric Dumazet 
Signed-off-by: David S. Miller

pkt_sched: sch_qfq: remove a useless invocation of qfq_update_eligible

2013-03-06T07:47:05+00:00

QFQ+ can select for service only 'eligible' aggregates, i.e.,
aggregates that would have started to be served also in the emulated
ideal system.  As a consequence, for QFQ+ to be work conserving, at
least one of the active aggregates must be eligible when it is time to
choose the next aggregate to serve.

The set of eligible aggregates is updated through the function
qfq_update_eligible(), which does guarantee that, after its
invocation, at least one of the active aggregates is eligible.
Because of this property, this function is invoked in
qfq_deactivate_agg() to guarantee that at least one of the active
aggregates is still eligible after an aggregate has been deactivated.
In particular, the critical case is when there are other active
aggregates, but the aggregate being deactivated happens to be the only
one eligible.

However, this precaution is not needed for QFQ+ to be work conserving,
because update_eligible() is always invoked also at the beginning of
qfq_choose_next_agg(). This patch removes the additional invocation of
update_eligible() in qfq_deactivate_agg().

Signed-off-by: Paolo Valente 
Reviewed-by: Fabio Checconi 
Signed-off-by: David S. Miller

pkt_sched: sch_qfq: do not allow virtual time to jump if an aggregate is in service

2013-03-06T07:47:05+00:00

By definition of (the algorithm of) QFQ+, the system virtual time must
be pushed up only if there is no 'eligible' aggregate, i.e. no
aggregate that would have started to be served also in the ideal
system emulated by QFQ+.  QFQ+ serves only eligible aggregates, hence
the aggregate currently in service is eligible.  As a consequence, to
decide whether there is no eligible aggregate, QFQ+ must also check
whether there is no aggregate in service.

Signed-off-by: Paolo Valente 
Reviewed-by: Fabio Checconi 
Signed-off-by: David S. Miller

pkt_sched: sch_qfq: prevent budget from wrapping around after a dequeue

2013-03-06T07:47:05+00:00

Aggregate budgets are computed so as to guarantee that, after an
aggregate has been selected for service, that aggregate has enough
budget to serve at least one maximum-size packet for the classes it
contains. For this reason, after a new aggregate has been selected
for service, its next packet is immediately dequeued, without any
further control.

The maximum packet size for a class, lmax, can be changed through
qfq_change_class(). In case the user sets lmax to a lower value than
the the size of some of the still-to-arrive packets, QFQ+ will
automatically push up lmax as it enqueues these packets.  This
automatic push up is likely to happen with TSO/GSO.

In any case, if lmax is assigned a lower value than the size of some
of the packets already enqueued for the class, then the following
problem may occur: the size of the next packet to dequeue for the
class may happen to be larger than lmax, after the aggregate to which
the class belongs has been just selected for service. In this case,
even the budget of the aggregate, which is an unsigned value, may be
lower than the size of the next packet to dequeue. After dequeueing
this packet and subtracting its size from the budget, the latter would
wrap around.

This fix prevents the budget from wrapping around after any packet
dequeue.

Signed-off-by: Paolo Valente 
Reviewed-by: Fabio Checconi 
Signed-off-by: David S. Miller

pkt_sched: sch_qfq: serve activated aggregates immediately if the scheduler is empty

2013-03-06T07:47:05+00:00

If no aggregate is in service, then the function qfq_dequeue() does
not dequeue any packet. For this reason, to guarantee QFQ+ to be work
conserving, a just-activated aggregate must be set as in service
immediately if it happens to be the only active aggregate.
This is done by the function qfq_enqueue().

Unfortunately, the function qfq_add_to_agg(), used to add a class to
an aggregate, does not perform this important additional operation.
In particular, if: 1) qfq_add_to_agg() is invoked to complete the move
of a class from a source aggregate, becoming, for this move, inactive,
to a destination aggregate, becoming instead active, and 2) the
destination aggregate becomes the only active aggregate, then this
aggregate is not however set as in service. QFQ+ remains then in a
non-work-conserving state until a new invocation of qfq_enqueue()
recovers the situation.

This fix solves the problem by moving the logic for setting an
aggregate as in service directly into the function qfq_activate_agg().
Hence, from whatever point qfq_activate_aggregate() is invoked, QFQ+
remains work conserving.  Since the more-complex logic of this new
version of activate_aggregate() is not necessary, in qfq_dequeue(), to
reschedule an aggregate that finishes its budget, then the aggregate
is now rescheduled by invoking directly the functions needed.

Signed-off-by: Paolo Valente 
Reviewed-by: Fabio Checconi 
Signed-off-by: David S. Miller

pkt_sched: sch_qfq: fix the update of eligible-group sets

2013-03-06T07:47:05+00:00

Between two invocations of make_eligible, the system virtual time may
happen to grow enough that, in its binary representation, a bit with
higher order than 31 flips. This happens especially with
TSO/GSO. Before this fix, the mask used in make_eligible was computed
as (1UL< 31.
The fix just replaces 1UL with 1ULL.

Signed-off-by: Paolo Valente 
Reviewed-by: Fabio Checconi 
Signed-off-by: David S. Miller

pkt_sched: sch_qfq: properly cap timestamps in charge_actual_service

2013-03-06T07:47:05+00:00

QFQ+ schedules the active aggregates in a group using a bucket list
(one list per group). The bucket in which each aggregate is inserted
depends on the aggregate's timestamps, and the number
of buckets in a group is enough to accomodate the possible (range of)
values of the timestamps of all the aggregates in the group. For this
property to hold, timestamps must however be computed correctly.  One
necessary condition for computing timestamps correctly is that the
number of bits dequeued for each aggregate, while the aggregate is in
service, does not exceed the maximum budget budgetmax assigned to the
aggregate.

For each aggregate, budgetmax is proportional to the number of classes
in the aggregate. If the number of classes of the aggregate is
decreased through qfq_change_class(), then budgetmax is decreased
automatically as well.  Problems may occur if the aggregate is in
service when budgetmax is decreased, because the current remaining
budget of the aggregate and/or the service already received by the
aggregate may happen to be larger than the new value of budgetmax.  In
this case, when the aggregate is eventually deselected and its
timestamps are updated, the aggregate may happen to have received an
amount of service larger than budgetmax.  This may cause the aggregate
to be assigned a higher virtual finish time than the maximum
acceptable value for the last bucket in the bucket list of the group.

This fix introduces a cap that addresses this issue.

Signed-off-by: Paolo Valente 
Reviewed-by: Fabio Checconi 
Signed-off-by: David S. Miller