Merge pull request #4028 from jayantjain93/low-memory-offset

additional memory reservation for gce cloud provider for low memory m...
kubernetes · Apr 22, 2021 · 8dc1afb · 8dc1afb
2 parents 3bfbc18 + 4d13cdd
commit 8dc1afb
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Showing 3 changed files with 19 additions and 12 deletions.
diff --git a/cluster-autoscaler/cloudprovider/gce/reserved.go b/cluster-autoscaler/cloudprovider/gce/reserved.go
@@ -66,6 +66,10 @@ const (
 	// ubuntuSpecificOffset is a constant value that is additionally added to Ubuntu
 	// based distributions as reserved memory
 	ubuntuSpecificOffset = 4 * MiB
+	// lowMemoryOffset is an additional offset added for lower memory sized machines
+	lowMemoryOffset = 8 * MiB
+	// lowMemoryThreshold is the threshold to apply lowMemoryOffset
+	lowMemoryThreshold = 8 * GiB
 )
 
 // EvictionHard is the struct used to keep parsed values for eviction
@@ -97,6 +101,9 @@ func CalculateKernelReserved(physicalMemory int64, os OperatingSystem, osDistrib
 			reserved += int64(math.Min(correctionConstant*float64(physicalMemory), maximumCorrectionValue))
 			reserved += ubuntuSpecificOffset
 		}
+		if physicalMemory <= lowMemoryThreshold {
+			reserved += lowMemoryOffset
+		}
 
 		return reserved
 	case OperatingSystemWindows:

diff --git a/cluster-autoscaler/cloudprovider/gce/reserved_test.go b/cluster-autoscaler/cloudprovider/gce/reserved_test.go
@@ -33,27 +33,27 @@ func TestCalculateKernelReservedLinux(t *testing.T) {
 	testCases := []testCase{
 		{
 			physicalMemory: 256 * MiB,
-			reservedMemory: 4*MiB + kernelReservedMemory,
+			reservedMemory: 4*MiB + kernelReservedMemory + lowMemoryOffset,
 			osDistribution: OperatingSystemDistributionCOS,
 		},
 		{
 			physicalMemory: 2 * GiB,
-			reservedMemory: 32*MiB + kernelReservedMemory,
+			reservedMemory: 32*MiB + kernelReservedMemory + lowMemoryOffset,
 			osDistribution: OperatingSystemDistributionCOS,
 		},
 		{
 			physicalMemory: 3 * GiB,
-			reservedMemory: 48*MiB + kernelReservedMemory,
+			reservedMemory: 48*MiB + kernelReservedMemory + lowMemoryOffset,
 			osDistribution: OperatingSystemDistributionCOS,
 		},
 		{
 			physicalMemory: 3.25 * GiB,
-			reservedMemory: 52*MiB + kernelReservedMemory + swiotlbReservedMemory,
+			reservedMemory: 52*MiB + kernelReservedMemory + swiotlbReservedMemory + lowMemoryOffset,
 			osDistribution: OperatingSystemDistributionCOS,
 		},
 		{
 			physicalMemory: 4 * GiB,
-			reservedMemory: 64*MiB + kernelReservedMemory + swiotlbReservedMemory,
+			reservedMemory: 64*MiB + kernelReservedMemory + swiotlbReservedMemory + lowMemoryOffset,
 			osDistribution: OperatingSystemDistributionCOS,
 		},
 		{
@@ -63,27 +63,27 @@ func TestCalculateKernelReservedLinux(t *testing.T) {
 		},
 		{
 			physicalMemory: 256 * MiB,
-			reservedMemory: 4*MiB + kernelReservedMemory,
+			reservedMemory: 4*MiB + kernelReservedMemory + lowMemoryOffset,
 			osDistribution: OperatingSystemDistributionUbuntu,
 		},
 		{
 			physicalMemory: 2 * GiB,
-			reservedMemory: 32*MiB + kernelReservedMemory,
+			reservedMemory: 32*MiB + kernelReservedMemory + lowMemoryOffset,
 			osDistribution: OperatingSystemDistributionUbuntu,
 		},
 		{
 			physicalMemory: 3 * GiB,
-			reservedMemory: 48*MiB + kernelReservedMemory,
+			reservedMemory: 48*MiB + kernelReservedMemory + lowMemoryOffset,
 			osDistribution: OperatingSystemDistributionUbuntu,
 		},
 		{
 			physicalMemory: 3.25 * GiB,
-			reservedMemory: 52*MiB + kernelReservedMemory + swiotlbReservedMemory,
+			reservedMemory: 52*MiB + kernelReservedMemory + swiotlbReservedMemory + lowMemoryOffset,
 			osDistribution: OperatingSystemDistributionUbuntu,
 		},
 		{
 			physicalMemory: 4 * GiB,
-			reservedMemory: 64*MiB + kernelReservedMemory + swiotlbReservedMemory,
+			reservedMemory: 64*MiB + kernelReservedMemory + swiotlbReservedMemory + lowMemoryOffset,
 			osDistribution: OperatingSystemDistributionUbuntu,
 		},
 		{

diff --git a/cluster-autoscaler/cloudprovider/gce/templates_test.go b/cluster-autoscaler/cloudprovider/gce/templates_test.go
@@ -455,13 +455,13 @@ func TestBuildCapacityMemory(t *testing.T) {
 			physicalCpu:            1,
 			physicalMemory:         2 * units.GiB,
 			os:                     OperatingSystemLinux,
-			expectedCapacityMemory: 2*units.GiB - 32*units.MiB - kernelReservedMemory - int64(math.Min(correctionConstant*float64(2*units.GiB), maximumCorrectionValue)),
+			expectedCapacityMemory: 2*units.GiB - 32*units.MiB - kernelReservedMemory - int64(math.Min(correctionConstant*float64(2*units.GiB), maximumCorrectionValue)) - lowMemoryOffset,
 		},
 		{
 			physicalCpu:            2,
 			physicalMemory:         4 * units.GiB,
 			os:                     OperatingSystemLinux,
-			expectedCapacityMemory: 4*units.GiB - 64*units.MiB - kernelReservedMemory - swiotlbReservedMemory - int64(math.Min(correctionConstant*float64(4*units.GiB), maximumCorrectionValue)),
+			expectedCapacityMemory: 4*units.GiB - 64*units.MiB - kernelReservedMemory - swiotlbReservedMemory - int64(math.Min(correctionConstant*float64(4*units.GiB), maximumCorrectionValue)) - lowMemoryOffset,
 		},
 		{
 			physicalCpu:            32,