kvm/amd64: don't limit a number of VCPU-s by GOMAXPROCS

We see some performance degradation after e98016263b
where we started limit a number of vcpu-s.

The memory limit for TestMemLimit is increased from 50MB to 128MB.
It is required because more vcpu-s require more memory. Before this
change, the test container required 46MB (8 vcpus). After this change,
the test container requires 60MB (328 vcpu-s).

PiperOrigin-RevId: 428879037

pkg/sentry/platform/kvm/machine_amd64.go

@@ -21,7 +21,6 @@ import (
 	"fmt"
 	"math/big"
 	"reflect"
-	"runtime"
 	"runtime/debug"
 
 	"golang.org/x/sys/unix"
@@ -489,10 +488,6 @@ func (m *machine) getMaxVCPU() {
 	} else {
 		m.maxVCPUs = int(maxVCPUs)
 	}
-	rCPUs := runtime.GOMAXPROCS(0)
-	if rCPUs < m.maxVCPUs {
-		m.maxVCPUs = rCPUs
-	}
 }
 
 func archPhysicalRegions(physicalRegions []physicalRegion) []physicalRegion {

test/e2e/integration_test.go

@@ -295,7 +295,7 @@ func TestMemLimit(t *testing.T) {
 	d := dockerutil.MakeContainer(ctx, t)
 	defer d.CleanUp(ctx)
 
-	allocMemoryKb := 50 * 1024
+	allocMemoryKb := 128 * 1024
 	opts := dockerutil.RunOpts{
 		Image:  "basic/alpine",
 		Memory: allocMemoryKb * 1024, // In bytes.