balloons: hideHyperthreads balloon type option and annotation

cmd/plugins/balloons/policy/balloons-policy.go

@@ -17,6 +17,7 @@ package balloons
 import (
 	"fmt"
 	"path/filepath"
+	"strconv"
 
 	cfgapi "github.com/containers/nri-plugins/pkg/apis/config/v1alpha1/resmgr/policy/balloons"
 	"github.com/containers/nri-plugins/pkg/cpuallocator"
@@ -41,6 +42,8 @@ const (
 
 	// balloonKey is a pod annotation key, the value is a pod balloon name.
 	balloonKey = "balloon." + PolicyName + "." + kubernetes.ResmgrKeyNamespace
+	// hideHyperthreadsKey is a pod annotation key for pod/container-specific hyperthread allowance.
+	hideHyperthreadsKey = "hide-hyperthreads." + kubernetes.ResmgrKeyNamespace
 	// reservedBalloonDefName is the name in the reserved balloon definition.
 	reservedBalloonDefName = "reserved"
 	// defaultBalloonDefName is the name in the default balloon definition.
@@ -1313,16 +1316,38 @@ func (p *balloons) resizeBalloon(bln *Balloon, newMilliCpus int) error {
 
 func (p *balloons) updatePinning(blns ...*Balloon) {
 	for _, bln := range blns {
-		cpus := bln.Cpus.Union(bln.SharedIdleCpus)
-		bln.Mems = p.closestMems(cpus)
+		var cpusNoHt cpuset.CPUSet
+		var allowedCpus cpuset.CPUSet
+		pinnableCpus := bln.Cpus.Union(bln.SharedIdleCpus)
+		bln.Mems = p.closestMems(pinnableCpus)
 		for _, cID := range bln.ContainerIDs() {
 			if c, ok := p.cch.LookupContainer(cID); ok {
-				p.pinCpuMem(c, cpus, bln.Mems)
+				if runWithoutHyperthreads(c, bln) {
+					if cpusNoHt.Size() == 0 {
+						cpusNoHt = p.cpuTree.system().SingleThreadForCPUs(pinnableCpus)
+					}
+					allowedCpus = cpusNoHt
+				} else {
+					allowedCpus = pinnableCpus
+				}
+				p.pinCpuMem(c, allowedCpus, bln.Mems)
 			}
 		}
 	}
 }
 
+// runWithoutHyperthreads returns true if a container should run using
+// only single hyperthread from each physical core.
+func runWithoutHyperthreads(c cache.Container, bln *Balloon) bool {
+	// Is balloon type configuration overridden by annotation?
+	if value, ok := c.GetEffectiveAnnotation(hideHyperthreadsKey); ok {
+		if hide, err := strconv.ParseBool(value); err == nil {
+			return hide
+		}
+	}
+	return bln.Def.HideHyperthreads != nil && *bln.Def.HideHyperthreads
+}
+
 // shareIdleCpus adds addCpus and removes removeCpus to those balloons
 // that whose containers are allowed to use shared idle CPUs. Returns
 // balloons that will need re-pinning.

cmd/plugins/balloons/policy/cputree.go

@@ -32,7 +32,7 @@ type cpuTreeNode struct {
 	parent   *cpuTreeNode
 	children []*cpuTreeNode
 	cpus     cpuset.CPUSet // union of CPUs of child nodes
-
+	sys      system.System
 }
 
 // cpuTreeNodeAttributes contains various attributes of a CPU tree
@@ -97,6 +97,13 @@ func (t *cpuTreeNode) PrettyPrint() string {
 	return strings.Join(lines, "\n")
 }
 
+func (t *cpuTreeNode) system() system.System {
+	if t.sys != nil || t.parent == nil {
+		return t.sys
+	}
+	return t.parent.system()
+}
+
 // String returns cpuTreeNodeAttributes as a string.
 func (tna cpuTreeNodeAttributes) String() string {
 	return fmt.Sprintf("%s{%d,%v,%d,%d}", tna.t.name, tna.depth,
@@ -247,6 +254,7 @@ func NewCpuTreeFromSystem() (*cpuTreeNode, error) {
 	}
 	// TODO: split deep nested loops into functions
 	sysTree := NewCpuTree("system")
+	sysTree.sys = sys
 	sysTree.level = CPUTopologyLevelSystem
 	for _, packageID := range sys.PackageIDs() {
 		packageTree := NewCpuTree(fmt.Sprintf("p%d", packageID))

config/crd/bases/config.nri_balloonspolicies.yaml

@@ -91,6 +91,21 @@ spec:
                         ${pod/labels/mylabel} will be substituted with
                         corresponding values.
                       type: string
+                    hideHyperthreads:
+                      description: |-
+                        HideHyperthreads allows containers in a balloon use only
+                        one hyperthread from each physical CPU core in the
+                        balloon. For instance, if a balloon contains 16 logical
+                        CPUs from 8 physical cores and this option is true, then
+                        containers in the balloon will be allowed to use 8 logical
+                        CPUs, one from each physical core. This option is best used
+                        with PreferSpreadOnPhysicalCores=false in order to allocate
+                        all hyperthreads of each physical core into the same
+                        balloon, but allow containers to use only one hyperthread
+                        from each core. This will ensure that hidden hyperthreads
+                        will remain completely idle as they cannot be allocated to
+                        other balloons.
+                      type: boolean
                     matchExpressions:
                       description: |-
                         MatchExpressions specifies one or more expressions which are evaluated

deployment/helm/balloons/crds/config.nri_balloonspolicies.yaml

@@ -91,6 +91,21 @@ spec:
                         ${pod/labels/mylabel} will be substituted with
                         corresponding values.
                       type: string
+                    hideHyperthreads:
+                      description: |-
+                        HideHyperthreads allows containers in a balloon use only
+                        one hyperthread from each physical CPU core in the
+                        balloon. For instance, if a balloon contains 16 logical
+                        CPUs from 8 physical cores and this option is true, then
+                        containers in the balloon will be allowed to use 8 logical
+                        CPUs, one from each physical core. This option is best used
+                        with PreferSpreadOnPhysicalCores=false in order to allocate
+                        all hyperthreads of each physical core into the same
+                        balloon, but allow containers to use only one hyperthread
+                        from each core. This will ensure that hidden hyperthreads
+                        will remain completely idle as they cannot be allocated to
+                        other balloons.
+                      type: boolean
                     matchExpressions:
                       description: |-
                         MatchExpressions specifies one or more expressions which are evaluated

docs/resource-policy/policy/balloons.md

@@ -181,6 +181,17 @@ Balloons policy parameters:
     - `numa`: ...in the same numa node(s) as the balloon.
     - `core`: ...allowed to use idle CPU threads in the same cores with
       the balloon.
+  - `hideHyperthreads`: "soft" disable hyperthreads. If `true`, only
+    one hyperthread from every physical CPU core in the balloon is
+    allowed to be used by containers in the balloon. Hidden
+    hyperthreads are not available to any container in the system
+    either. If containers in the balloon are allowed to share idle
+    CPUs (see `shareIdleCPUsInSame`), hyperthreads of idle CPUs, too,
+    are hidden from the containers. If containers in another balloon
+    share the same idle CPUs, those containers are allowed to use both
+    hyperthreads of the idle CPUs if `hideHyperthreads` is `false` for
+    the other balloon. The default is `false`: containers are allowed
+    to use all hyperthreads of balloon's CPUs and shared idle CPUs.
   - `preferSpreadOnPhysicalCores` overrides the policy level option
     with the same name in the scope of this balloon type.
   - `preferCloseToDevices` prefers creating new balloons close to
@@ -301,6 +312,28 @@ memory.preserve.resource-policy.nri.io/pod: "true"
 memory.preserve.resource-policy.nri.io: "true"
 ```
 
+### Selectively Disabling Hyperthreading
+
+If a container opts to hide hyperthreads, it is allowed to use only
+one hyperthread from every physical CPU core allocated to it. Note
+that as a result the container may be allowed to run on only half of
+the CPUs it has requested. In case of workloads that do not benefit
+from hyperthreading this nevertheless results in better performance
+compared to running on all hyperthreads of the same CPU cores. If
+container's CPU allocation is exclusive, no other container can run on
+hidden hyperthreads either.
+
+```yaml
+metadata:
+  annotations:
+    # allow the "LLM" container to use only single thread per physical CPU core
+    hide-hyperthreads.resource-policy.nri.io/container.LLM: "true"
+```
+
+The `hide-hyperthreads` pod annotation overrides the
+`hideHyperthreads` balloon type parameter value for selected
+containers in the pod.
+
 ## Metrics and Debugging
 
 In order to enable more verbose logging and metrics exporting from the

pkg/apis/config/v1alpha1/resmgr/policy/balloons/config.go

@@ -156,6 +156,19 @@ type BalloonDef struct {
 	// PreferSpreadOnPhysicalCores is the balloon type specific
 	// parameter of the policy level parameter with the same name.
 	PreferSpreadOnPhysicalCores *bool `json:"preferSpreadOnPhysicalCores,omitempty"`
+	// HideHyperthreads allows containers in a balloon use only
+	// one hyperthread from each physical CPU core in the
+	// balloon. For instance, if a balloon contains 16 logical
+	// CPUs from 8 physical cores and this option is true, then
+	// containers in the balloon will be allowed to use 8 logical
+	// CPUs, one from each physical core. This option is best used
+	// with PreferSpreadOnPhysicalCores=false in order to allocate
+	// all hyperthreads of each physical core into the same
+	// balloon, but allow containers to use only one hyperthread
+	// from each core. This will ensure that hidden hyperthreads
+	// will remain completely idle as they cannot be allocated to
+	// other balloons.
+	HideHyperthreads *bool `json:"hideHyperthreads,omitempty"`
 	// AllocatorTopologyBalancing is the balloon type specific
 	// parameter of the policy level parameter with the same name.
 	AllocatorTopologyBalancing *bool `json:"allocatorTopologyBalancing,omitempty"`

test/e2e/policies.test-suite/balloons/balloons-busybox.yaml.in

@@ -4,7 +4,9 @@ metadata:
   name: ${NAME}
   $(if [ -n "$POD_ANNOTATION" ]; then echo "
   annotations:
-    $POD_ANNOTATION
+    $(for ann in "${POD_ANNOTATION[@]}"; do echo "
+    $ann
+    "; done)
   "; fi)
   labels:
     app: ${NAME}

test/e2e/policies.test-suite/balloons/n4c16/test01-basic-placement/code.var.sh

@@ -46,11 +46,17 @@ cleanup
 
 # pod4: first two containers to the first instance, 3rd to new four-cpu instance
 CPUREQ="3" MEMREQ="" CPULIM="3" MEMLIM=""
-POD_ANNOTATION="balloon.balloons.resource-policy.nri.io: four-cpu" CONTCOUNT=3 create balloons-busybox
+POD_ANNOTATION=(
+    "balloon.balloons.resource-policy.nri.io: four-cpu"
+    "hide-hyperthreads.resource-policy.nri.io/container.pod4c1: \"true\""
+)
+CONTCOUNT=3 create balloons-busybox
+unset POD_ANNOTATION
 report allowed
-verify 'cpus["pod4c0"] == cpus["pod4c1"]' \
+verify 'cpus["pod4c1"].issubset(cpus["pod4c0"])' \
        'disjoint_sets(cpus["pod4c2"], cpus["pod4c0"])' \
        'len(cpus["pod4c0"]) == 6' \
+       'len(cpus["pod4c1"]) == 3' \
        'len(cpus["pod4c2"]) == 4'
 
 cleanup

test/e2e/policies.test-suite/balloons/n4c16/test02-prometheus-metrics/balloons-metrics.cfg

@@ -5,6 +5,7 @@ config:
     - name: full-core
       minCPUs: 2
       maxCPUs: 2
+      hideHyperthreads: true
       cpuClass: normal
 
     - name: fast-dualcore

test/e2e/policies.test-suite/balloons/n4c16/test02-prometheus-metrics/code.var.sh

@@ -21,11 +21,19 @@ verify-metrics-has-no-line 'balloon_type="flex"'
 
 # pod0 in full-core[0]
 CPUREQ="100m" MEMREQ="100M" CPULIM="100m" MEMLIM="100M"
-POD_ANNOTATION="balloon.balloons.resource-policy.nri.io: full-core" CONTCOUNT=2 create balloons-busybox
+POD_ANNOTATION=(
+    "balloon.balloons.resource-policy.nri.io: full-core"
+    "hide-hyperthreads.resource-policy.nri.io/container.pod0c1: \"false\""
+)
+CONTCOUNT=2 create balloons-busybox
+unset POD_ANNOTATION
 report allowed
 verify-metrics-has-line 'balloon="default\[0\]"'
 verify-metrics-has-line 'balloon="reserved\[0\]"'
 verify-metrics-has-line 'balloons{balloon="full-core\[0\]",balloon_type="full-core",containers="pod0/pod0c0,pod0/pod0c1",cpu_class="normal",cpus=".*",cpus_allowed=".*",cpus_allowed_count="2",cpus_count="2",cpus_max="2",cpus_min="2",dies="p[01]d0",dies_count="1",groups="",mems="[0-3]",numas="p[01]d0n[0-3]",numas_count="1",packages="p[01]",packages_count="1",sharedidlecpus="",sharedidlecpus_count="0",tot_req_millicpu="(199|200)"} 2'
+verify 'len(cpus["pod0c0"]) == 1' \
+       'len(cpus["pod0c1"]) == 2' \
+       'cpus["pod0c0"].issubset(cpus["pod0c1"])'
 
 # pod1 in fast-dualcore[0]
 CPUREQ="200m" MEMREQ="" CPULIM="200m" MEMLIM=""