132 lines
3.3 KiB
Go
132 lines
3.3 KiB
Go
package scheduler
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import (
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"fmt"
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"math"
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"github.com/hashicorp/nomad/nomad/structs"
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)
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// deviceAllocator is used to allocate devices to allocations. The allocator
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// tracks availability as to not double allocate devices.
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type deviceAllocator struct {
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*structs.DeviceAccounter
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ctx Context
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}
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// newDeviceAllocator returns a new device allocator. The node is used to
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// populate the set of available devices based on what healthy device instances
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// exist on the node.
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func newDeviceAllocator(ctx Context, n *structs.Node) *deviceAllocator {
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return &deviceAllocator{
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ctx: ctx,
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DeviceAccounter: structs.NewDeviceAccounter(n),
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}
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}
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// AssignDevice takes a device request and returns an assignment as well as a
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// score for the assignment. If no assignment could be made, an error is
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// returned explaining why.
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func (d *deviceAllocator) AssignDevice(ask *structs.RequestedDevice) (out *structs.AllocatedDeviceResource, score float64, err error) {
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// Try to hot path
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if len(d.Devices) == 0 {
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return nil, 0.0, fmt.Errorf("no devices available")
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}
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if ask.Count == 0 {
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return nil, 0.0, fmt.Errorf("invalid request of zero devices")
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}
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// Hold the current best offer
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var offer *structs.AllocatedDeviceResource
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var offerScore float64
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var matchedWeights float64
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// Determine the devices that are feasible based on availability and
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// constraints
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for id, devInst := range d.Devices {
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// Check if we have enough unused instances to use this
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assignable := uint64(0)
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for _, v := range devInst.Instances {
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if v == 0 {
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assignable++
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}
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}
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// This device doesn't have enough instances
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if assignable < ask.Count {
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continue
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}
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// Check if the device works
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if !nodeDeviceMatches(d.ctx, devInst.Device, ask) {
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continue
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}
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// Score the choice
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var choiceScore float64
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// Track the sum of matched affinity weights in a separate variable
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// We return this if this device had the best score compared to other devices considered
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var sumMatchedWeights float64
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if l := len(ask.Affinities); l != 0 {
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totalWeight := 0.0
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for _, a := range ask.Affinities {
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// Resolve the targets
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lVal, lOk := resolveDeviceTarget(a.LTarget, devInst.Device)
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rVal, rOk := resolveDeviceTarget(a.RTarget, devInst.Device)
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totalWeight += math.Abs(float64(a.Weight))
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// Check if satisfied
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if !checkAttributeAffinity(d.ctx, a.Operand, lVal, rVal, lOk, rOk) {
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continue
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}
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choiceScore += float64(a.Weight)
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sumMatchedWeights += float64(a.Weight)
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}
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// normalize
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choiceScore /= totalWeight
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}
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// Only use the device if it is a higher score than we have already seen
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if offer != nil && choiceScore < offerScore {
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continue
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}
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// Set the new highest score
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offerScore = choiceScore
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// Set the new sum of matching affinity weights
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matchedWeights = sumMatchedWeights
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// Build the choice
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offer = &structs.AllocatedDeviceResource{
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Vendor: id.Vendor,
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Type: id.Type,
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Name: id.Name,
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DeviceIDs: make([]string, 0, ask.Count),
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}
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assigned := uint64(0)
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for id, v := range devInst.Instances {
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if v == 0 && assigned < ask.Count {
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assigned++
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offer.DeviceIDs = append(offer.DeviceIDs, id)
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if assigned == ask.Count {
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break
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}
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}
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}
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}
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// Failed to find a match
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if offer == nil {
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return nil, 0.0, fmt.Errorf("no devices match request")
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}
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return offer, matchedWeights, nil
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}
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