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fix issues with bandwidth plugin and htb introduction #1097

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fix issues with bandwidth plugin and htb introduction #1097

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cf33cbd
fix issues with quantum
h0nIg Sep 20, 2024
874cd28
revert txqueue due to kernel performance issues
h0nIg Oct 10, 2024
9975b5d
fix tests
h0nIg Oct 10, 2024
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45 changes: 31 additions & 14 deletions plugins/meta/bandwidth/ifb_creator.go
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Original file line number Diff line number Diff line change
Expand Up @@ -33,18 +33,22 @@ const (
UnShapedClassMinorID uint16 = 1
)

func CreateIfb(ifbDeviceName string, mtu int, qlen int) error {
if qlen < 1000 {
qlen = 1000
}
func CreateIfb(ifbDeviceName string, mtu int, _ int) error {
// numtxqueues mismatch between veth and ifb is causing performance issues
// (similar to mismatch between Host-veth0 and Container peer: https://github.com/torvalds/linux/blob/9d3684c24a5232c2d7ea8f8a3e60fe235e6a9867/drivers/net/veth.c#L1199-L1206)
// do not enable until netlink library offer setting numtxqueues on a ifb device
// if qlen < 1000 {
// qlen = 1000
// }

linkAttrs := netlink.NewLinkAttrs()
linkAttrs.Name = ifbDeviceName
linkAttrs.Flags = net.FlagUp
linkAttrs.MTU = mtu
// linkAttrs.TxQLen = qlen

err := netlink.LinkAdd(&netlink.Ifb{
LinkAttrs: netlink.LinkAttrs{
Name: ifbDeviceName,
Flags: net.FlagUp,
MTU: mtu,
TxQLen: qlen,
},
LinkAttrs: linkAttrs,
})
if err != nil {
return fmt.Errorf("adding link: %s", err)
Expand Down Expand Up @@ -75,7 +79,7 @@ func CreateIngressQdisc(rateInBits, burstInBits uint64, excludeSubnets []string,
exclude = true
}

return createHTB(rateInBits, burstInBits, hostDevice.Attrs().Index, subnets, exclude)
return createHTB(rateInBits, burstInBits, hostDevice.Attrs().MTU, hostDevice.Attrs().Index, subnets, exclude)
}

func CreateEgressQdisc(rateInBits, burstInBits uint64, excludeSubnets []string, includeSubnets []string, hostDeviceName string, ifbDeviceName string) error {
Expand Down Expand Up @@ -134,15 +138,15 @@ func CreateEgressQdisc(rateInBits, burstInBits uint64, excludeSubnets []string,
}

// throttle traffic on ifb device
err = createHTB(rateInBits, burstInBits, ifbDevice.Attrs().Index, subnets, exclude)
err = createHTB(rateInBits, burstInBits, ifbDevice.Attrs().MTU, ifbDevice.Attrs().Index, subnets, exclude)
if err != nil {
// egress from the container/netns pov = ingress from the main netns/host pov
return fmt.Errorf("create htb container egress qos rules: %s", err)
}
return nil
}

func createHTB(rateInBits, burstInBits uint64, linkIndex int, subnets []string, excludeSubnets bool) error {
func createHTB(rateInBits, burstInBits uint64, mtu int, linkIndex int, subnets []string, excludeSubnets bool) error {
// Netlink struct fields are not clear, let's use shell

defaultClassID := UnShapedClassMinorID
Expand All @@ -160,7 +164,7 @@ func createHTB(rateInBits, burstInBits uint64, linkIndex int, subnets []string,
Parent: netlink.HANDLE_ROOT,
},
Defcls: uint32(defaultClassID),
// No idea what these are so let's keep the default values from source code...
// Keep the default values from source code
Version: 3,
Rate2Quantum: 10,
}
Expand All @@ -184,6 +188,12 @@ func createHTB(rateInBits, burstInBits uint64, linkIndex int, subnets []string,
Handle: netlink.MakeHandle(1, ShapedClassMinorID),
Parent: netlink.MakeHandle(1, 0),
},
// maximum bytes per cycle to dequeue, kernel is warning and limiting unreasonable values
// should be set to MTU + hardware header length of 14 bytes to avoid bursts which may cause subsequent txqueuelen drops
// https://github.com/torvalds/linux/blob/baeb9a7d8b60b021d907127509c44507539c15e5/net/sched/sch_htb.c#L2037
// https://github.com/torvalds/linux/blob/baeb9a7d8b60b021d907127509c44507539c15e5/net/sched/sch_htb.c#L2052-L2055
Quantum: uint32(mtu + 14),

Rate: rateInBytes,
Buffer: bufferInBytes,
// Let's set up the "burst" rate to twice the specified rate
Expand All @@ -206,8 +216,15 @@ func createHTB(rateInBits, burstInBits uint64, linkIndex int, subnets []string,
Handle: netlink.MakeHandle(1, UnShapedClassMinorID),
Parent: qdisc.Handle,
},
// maximum bytes per cycle to dequeue, kernel is warning and limiting unreasonable values
// should be set to MTU + hardware header length of 14 bytes to avoid bursts which may cause subsequent txqueuelen drops
// https://github.com/torvalds/linux/blob/baeb9a7d8b60b021d907127509c44507539c15e5/net/sched/sch_htb.c#L2037
// https://github.com/torvalds/linux/blob/baeb9a7d8b60b021d907127509c44507539c15e5/net/sched/sch_htb.c#L2052-L2055
Quantum: uint32(mtu + 14),

Rate: bigRate,
Ceil: bigRate,

// No need for any burst, the minimum buffer size in q_htb.c should be enough to handle the rate which
// is already more than enough
}
Expand Down