virtiofs: Add cache size option

Add VirtioFSCacheSize aka virtio_fs_cache_size option
to set the size (in MiB) of the DAX cache.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Makefile

@@ -158,6 +158,8 @@ DEFENTROPYSOURCE := /dev/urandom
 DEFDISABLEBLOCK := false
 DEFSHAREDFS := virtio-9p
 DEFVIRTIOFSDAEMON :=
+# Default DAX mapping cache size in MiB
+DEFVIRTIOFSCACHESIZE := 8192
 DEFENABLEIOTHREADS := false
 DEFENABLEMEMPREALLOC := false
 DEFENABLEHUGEPAGES := false
@@ -324,6 +326,7 @@ USER_VARS += DEFBLOCKSTORAGEDRIVER_FC
 USER_VARS += DEFBLOCKSTORAGEDRIVER_QEMU
 USER_VARS += DEFSHAREDFS
 USER_VARS += DEFVIRTIOFSDAEMON
+USER_VARS += DEFVIRTIOFSCACHESIZE
 USER_VARS += DEFENABLEIOTHREADS
 USER_VARS += DEFENABLEMEMPREALLOC
 USER_VARS += DEFENABLEHUGEPAGES
@@ -462,6 +465,7 @@ $(GENERATED_FILES): %: %.in $(MAKEFILE_LIST) VERSION .git-commit
 		-e "s|@DEFBLOCKSTORAGEDRIVER_QEMU@|$(DEFBLOCKSTORAGEDRIVER_QEMU)|g" \
 		-e "s|@DEFSHAREDFS@|$(DEFSHAREDFS)|g" \
 		-e "s|@DEFVIRTIOFSDAEMON@|$(DEFVIRTIOFSDAEMON)|g" \
+		-e "s|@DEFVIRTIOFSCACHESIZE@|$(DEFVIRTIOFSCACHESIZE)|g" \
 		-e "s|@DEFENABLEIOTHREADS@|$(DEFENABLEIOTHREADS)|g" \
 		-e "s|@DEFENABLEMEMPREALLOC@|$(DEFENABLEMEMPREALLOC)|g" \
 		-e "s|@DEFENABLEHUGEPAGES@|$(DEFENABLEHUGEPAGES)|g" \

cli/config/configuration-qemu.toml.in

@@ -105,6 +105,9 @@ shared_fs = "@DEFSHAREDFS@"
 # Path to vhost-user-fs daemon.
 virtio_fs_daemon = "@DEFVIRTIOFSDAEMON@"
 
+# Default size of DAX cache in MiB
+virtio_fs_cache_size = @DEFVIRTIOFSCACHESIZE@
+
 # Block storage driver to be used for the hypervisor in case the container
 # rootfs is backed by a block device. This is virtio-scsi, virtio-blk
 # or nvdimm.

pkg/katautils/config.go

@@ -94,6 +94,7 @@ type hypervisor struct {
 	EntropySource           string `toml:"entropy_source"`
 	SharedFS                string `toml:"shared_fs"`
 	VirtioFSDaemon          string `toml:"virtio_fs_daemon"`
+	VirtioFSCacheSize       uint32 `toml:"virtio_fs_cache_size"`
 	BlockDeviceCacheSet     bool   `toml:"block_device_cache_set"`
 	BlockDeviceCacheDirect  bool   `toml:"block_device_cache_direct"`
 	BlockDeviceCacheNoflush bool   `toml:"block_device_cache_noflush"`
@@ -578,6 +579,7 @@ func newQemuHypervisorConfig(h hypervisor) (vc.HypervisorConfig, error) {
 		DisableBlockDeviceUse:   h.DisableBlockDeviceUse,
 		SharedFS:                sharedFS,
 		VirtioFSDaemon:          h.VirtioFSDaemon,
+		VirtioFSCacheSize:       h.VirtioFSCacheSize,
 		MemPrealloc:             h.MemPrealloc,
 		HugePages:               h.HugePages,
 		Mlock:                   !h.Swap,

virtcontainers/device/config/config.go

@@ -187,7 +187,8 @@ type VhostUserDeviceAttrs struct {
 	MacAddress string
 
 	// These are only meaningful for vhost user fs devices
-	Tag string
+	Tag       string
+	CacheSize uint32
 }
 
 // GetHostPathFunc is function pointer used to mock GetHostPath in tests.

virtcontainers/documentation/api/1.0/api.md

@@ -146,6 +146,9 @@ type HypervisorConfig struct {
 	// VirtioFSDaemon is the virtio-fs vhost-user daemon path
 	VirtioFSDaemon string
 
+	// VirtioFSCacheSize is the virtio-fs DAX cache size in MiB
+	VirtioFSCacheSize uint32
+
 	// KernelParams are additional guest kernel parameters.
 	KernelParams []Param
 

virtcontainers/hypervisor.go

@@ -170,6 +170,9 @@ type HypervisorConfig struct {
 	// MemOffset specifies memory space for nvdimm device
 	MemOffset uint32
 
+	// VirtioFSCacheSize is the DAX cache size in MiB
+	VirtioFSCacheSize uint32
+
 	// KernelParams are additional guest kernel parameters.
 	KernelParams []Param
 

virtcontainers/qemu.go

@@ -1376,8 +1376,9 @@ func (q *qemu) addDevice(devInfo interface{}, devType deviceType) error {
 			}
 
 			vhostDev := config.VhostUserDeviceAttrs{
-				Tag:  v.MountTag,
-				Type: config.VhostUserFS,
+				Tag:       v.MountTag,
+				Type:      config.VhostUserFS,
+				CacheSize: q.config.VirtioFSCacheSize,
 			}
 			vhostDev.SocketPath = sockPath
 			vhostDev.DevID = id

virtcontainers/qemu_arch_base.go

@@ -530,6 +530,7 @@ func (q *qemuArchBase) appendVhostUserDevice(devices []govmmQemu.Device, attr co
 	case config.VhostUserFS:
 		qemuVhostUserDevice.TypeDevID = utils.MakeNameID("fs", attr.DevID, maxDevIDSize)
 		qemuVhostUserDevice.Tag = attr.Tag
+		qemuVhostUserDevice.CacheSize = attr.CacheSize
 	}
 
 	qemuVhostUserDevice.VhostUserType = govmmQemu.DeviceDriver(attr.Type)