Merge pull request #1393 from ernado:cpu-num-from-quota

PiperOrigin-RevId: 286068605

1 files changed, 21 insertions, 0 deletions

diff --git a/runsc/sandbox/sandbox.go b/runsc/sandbox/sandbox.go
index 805233184..ce1452b87 100644
--- a/runsc/sandbox/sandbox.go
+++ b/runsc/sandbox/sandbox.go
@@ -18,6 +18,7 @@ package sandbox
 import (
 	"context"
 	"fmt"
+	"math"
 	"os"
 	"os/exec"
 	"strconv"
@@ -631,6 +632,26 @@ func (s *Sandbox) createSandboxProcess(conf *boot.Config, args *Args, startSyncF
 		if err != nil {
 			return fmt.Errorf("getting cpu count from cgroups: %v", err)
 		}
+		if conf.CPUNumFromQuota {
+			// Dropping below 2 CPUs can trigger application to disable
+			// locks that can lead do hard to debug errors, so just
+			// leaving two cores as reasonable default.
+			const minCPUs = 2
+
+			quota, err := s.Cgroup.CPUQuota()
+			if err != nil {
+				return fmt.Errorf("getting cpu qouta from cgroups: %v", err)
+			}
+			if n := int(math.Ceil(quota)); n > 0 {
+				if n < minCPUs {
+					n = minCPUs
+				}
+				if n < cpuNum {
+					// Only lower the cpu number.
+					cpuNum = n
+				}
+			}
+		}
 		cmd.Args = append(cmd.Args, "--cpu-num", strconv.Itoa(cpuNum))
 
 		mem, err := s.Cgroup.MemoryLimit()