config: Add scsi_mod.scan=none for virtio-scsi

As per [1], the default scan mode of scsi is sync. kata-agent already scans the SCSI buses [2], changing it to none can reduce the guest boot time. =Before this patch= [ 0.113828] [ T1] scsi host0: Virtio SCSI HBA [ 0.134006] [ T1] tun: Universal TUN/TAP device driver, 1.6 =After this patch= [ 0.105891] [ T1] scsi host0: Virtio SCSI HBA [ 0.107868] [ T1] tun: Universal TUN/TAP device driver, 1.6 It reduces about 17ms on arm64 for virtio-scsi. This patch changes the default kernel parameter: 1. If user specifies the scan mode, use that 2. If user doesn't specify it, and the block device is virtio-scsi, use "none" by default [1] https://lwn.net/Articles/201898/ [2] https://github.com/kata-containers/agent/blob/649d44117a/device.go#L322 Fixes: #2560 Signed-off-by: Jia He <[email protected]
kata-containers · Apr 15, 2020 · 8c850d9 · 8c850d9
1 parent af24829
commit 8c850d9
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Showing 2 changed files with 18 additions and 4 deletions.
diff --git a/pkg/katautils/config.go b/pkg/katautils/config.go
@@ -977,7 +977,6 @@ func SetKernelParams(runtimeConfig *oci.RuntimeConfig) error {
 	if runtimeConfig.HypervisorConfig.Debug {
 		strParams := vc.SerializeParams(defaultKernelParams, "=")
 		formatted := strings.Join(strParams, " ")
-
 		kataUtilsLogger.WithField("default-kernel-parameters", formatted).Debug()
 	}
 
@@ -989,7 +988,18 @@ func SetKernelParams(runtimeConfig *oci.RuntimeConfig) error {
 
 	// first, add default values
 	for _, p := range defaultKernelParams {
-		if err := (runtimeConfig).AddKernelParam(p); err != nil {
+		if err := runtimeConfig.AddKernelParam(p); err != nil {
+			return err
+		}
+	}
+
+	// set the scsi scan mode to none for virtio-scsi
+	if runtimeConfig.HypervisorConfig.BlockDeviceDriver == config.VirtioSCSI {
+		p := vc.Param{
+			Key:   "scsi_mod.scan",
+			Value: "none",
+		}
+		if err := runtimeConfig.AddKernelParam(p); err != nil {
 			return err
 		}
 	}
@@ -1004,15 +1014,15 @@ func SetKernelParams(runtimeConfig *oci.RuntimeConfig) error {
 		params := vc.KataAgentKernelParams(agentConfig)
 
 		for _, p := range params {
-			if err := (runtimeConfig).AddKernelParam(p); err != nil {
+			if err := runtimeConfig.AddKernelParam(p); err != nil {
 				return err
 			}
 		}
 	}
 
 	// now re-add the user-specified values so that they take priority.
 	for _, p := range userKernelParams {
-		if err := (runtimeConfig).AddKernelParam(p); err != nil {
+		if err := runtimeConfig.AddKernelParam(p); err != nil {
 			return err
 		}
 	}

diff --git a/pkg/katautils/create_test.go b/pkg/katautils/create_test.go
@@ -208,6 +208,10 @@ func TestSetKernelParams(t *testing.T) {
 	err := SetKernelParams(&config)
 	assert.NoError(err)
 
+	config.HypervisorConfig.BlockDeviceDriver = "virtio-scsi"
+	err = SetKernelParams(&config)
+	assert.NoError(err)
+
 	if needSystemd(config.HypervisorConfig) {
 		assert.NotEmpty(config.HypervisorConfig.KernelParams)
 	}