1. docker
  2. Commit 09ee269d998ad04733ef577739fa051df9d3f12e
Browse code

devmapper: Add option for specifying the thin pool blocksize

Add dm.blocksize option that you can use with --storage-opt to set a
specific blocksize for the thin provisioning pool.

Also change the default dm-thin-pool blocksize from 64K to 512K. This
strikes a balance between the desire to have smaller blocksize given
docker's use of snapshots versus the desire to have more performance
that comes with using a larger blocksize. But if very small files will
be used on average the user is encouraged to override this default.

Docker-DCO-1.1-Signed-off-by: Mike Snitzer <snitzer@redhat.com> (github: snitm)

Mike Snitzer authored on 2014/06/21 00:53:18
Showing 3 changed files
daemon/graphdriver/devmapper/README.md
History View file @ 09ee269
... ... 
@@ -126,6 +126,14 @@ Here is the list of supported options:
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     ``docker -d --storage-opt dm.datadev=/dev/sdb1 --storage-opt dm.metadatadev=/dev/sdc1``
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+ *  `dm.blocksize`
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+
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+    Specifies a custom blocksize to use for the thin pool.
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+
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+    Example use:
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+
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+    ``docker -d --storage-opt dm.blocksize=64K``
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+
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  *  `dm.blkdiscard`
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     Enables or disables the use of blkdiscard when removing
daemon/graphdriver/devmapper/deviceset.go
History View file @ 09ee269
... ... 
@@ -28,6 +28,7 @@ var (
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 	DefaultDataLoopbackSize     int64  = 100 * 1024 * 1024 * 1024
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 	DefaultMetaDataLoopbackSize int64  = 2 * 1024 * 1024 * 1024
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 	DefaultBaseFsSize           uint64 = 10 * 1024 * 1024 * 1024
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+	DefaultThinpBlockSize       uint32  = 1024 // 512K = 1024 512b sectors
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 )
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 type DevInfo struct {
... ... 
@@ -78,6 +79,7 @@ type DeviceSet struct {
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 	dataDevice           string
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 	metadataDevice       string
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 	doBlkDiscard         bool
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+	thinpBlockSize       uint32
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 }
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 type DiskUsage struct {
... ... 
@@ -510,7 +512,7 @@ func (devices *DeviceSet) ResizePool(size int64) error {
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 	}
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 	// Reload with the new block sizes
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-	if err := reloadPool(devices.getPoolName(), dataloopback, metadataloopback); err != nil {
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+	if err := reloadPool(devices.getPoolName(), dataloopback, metadataloopback, devices.thinpBlockSize); err != nil {
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 		return fmt.Errorf("Unable to reload pool: %s", err)
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 	}
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... ... 
@@ -640,7 +642,7 @@ func (devices *DeviceSet) initDevmapper(doInit bool) error {
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 		}
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 		defer metadataFile.Close()
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-		if err := createPool(devices.getPoolName(), dataFile, metadataFile); err != nil {
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+		if err := createPool(devices.getPoolName(), dataFile, metadataFile, devices.thinpBlockSize); err != nil {
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 			return err
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 		}
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 	}
... ... 
@@ -1159,6 +1161,7 @@ func NewDeviceSet(root string, doInit bool, options []string) (*DeviceSet, error
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 		baseFsSize:           DefaultBaseFsSize,
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 		filesystem:           "ext4",
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 		doBlkDiscard:         true,
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+		thinpBlockSize:       DefaultThinpBlockSize,
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 	}
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 	foundBlkDiscard := false
... ... 
@@ -1206,6 +1209,13 @@ func NewDeviceSet(root string, doInit bool, options []string) (*DeviceSet, error
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 			if err != nil {
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 				return nil, err
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 			}
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+		case "dm.blocksize":
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+			size, err := units.RAMInBytes(val)
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+			if err != nil {
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+				return nil, err
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+			}
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+			// convert to 512b sectors
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+			devices.thinpBlockSize = uint32(size) >> 9
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 		default:
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 			return nil, fmt.Errorf("Unknown option %s\n", key)
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 		}
daemon/graphdriver/devmapper/devmapper.go
History View file @ 09ee269
... ... 
@@ -328,7 +328,7 @@ func BlockDeviceDiscard(path string) error {
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 }
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 // This is the programmatic example of "dmsetup create"
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-func createPool(poolName string, dataFile, metadataFile *os.File) error {
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+func createPool(poolName string, dataFile, metadataFile *os.File, poolBlockSize uint32) error {
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 	task, err := createTask(DeviceCreate, poolName)
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 	if task == nil {
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 		return err
... ... 
@@ -339,7 +339,7 @@ func createPool(poolName string, dataFile, metadataFile *os.File) error {
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 		return fmt.Errorf("Can't get data size %s", err)
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 	}
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-	params := metadataFile.Name() + " " + dataFile.Name() + " 128 32768 1 skip_block_zeroing"
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+	params := fmt.Sprintf("%s %s %d 32768 1 skip_block_zeroing", metadataFile.Name(), dataFile.Name(), poolBlockSize)
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 	if err := task.AddTarget(0, size/512, "thin-pool", params); err != nil {
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 		return fmt.Errorf("Can't add target %s", err)
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 	}
... ... 
@@ -358,7 +358,7 @@ func createPool(poolName string, dataFile, metadataFile *os.File) error {
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 	return nil
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 }
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-func reloadPool(poolName string, dataFile, metadataFile *os.File) error {
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+func reloadPool(poolName string, dataFile, metadataFile *os.File, poolBlockSize uint32) error {
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 	task, err := createTask(DeviceReload, poolName)
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 	if task == nil {
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 		return err
... ... 
@@ -369,7 +369,7 @@ func reloadPool(poolName string, dataFile, metadataFile *os.File) error {
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 		return fmt.Errorf("Can't get data size %s", err)
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 	}
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-	params := metadataFile.Name() + " " + dataFile.Name() + " 128 32768 1 skip_block_zeroing"
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+	params := fmt.Sprintf("%s %s %d 32768 1 skip_block_zeroing", metadataFile.Name(), dataFile.Name(), poolBlockSize)
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 	if err := task.AddTarget(0, size/512, "thin-pool", params); err != nil {
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 		return fmt.Errorf("Can't add target %s", err)
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 	}