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** Changed in: linux (Ubuntu)
Status: New => Incomplete
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https://bugs.launchpad.net/bugs/1582759
Title:
Unexpected low write rate with Lexar JumpDrive P20 64GB flash drives
Status in linux package in Ubuntu:
Incomplete
Bug description:
We are hitting an unexpected low write rate with Lexar JumpDrive P20
64GB flash drives connected via USB 3.0 on multiple machines and
across multiple kernels (3.13, 4.4). Expected is a write rate of 270
MB/s and we only get 45 MB/s. Under Mac OS X and Windows we get the
expected write rate of 270 MB/s. The read rate is as expected at 400
MB/s on all operating systems.
Lexar JumpDrive P20 details:
http://www.lexar.com/flash-drives/jumpdrive-p20
Tested machines:
* HP Z440
* Lenovo ThinkPad X250
Tested kernels:
* 3.13 (Trusty)
* 4.4 (Xenial)
lsusb details:
$ lsusb -t
/: Bus 03.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/4p, 5000M
|__ Port 2: Dev 2, If 0, Class=Mass Storage, Driver=usb-storage, 5000M
<-- USB 3.0
/: Bus 02.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/11p, 480M
|__ Port 1: Dev 2, If 0, Class=Vendor Specific Class, Driver=, 12M
|__ Port 8: Dev 4, If 0, Class=Video, Driver=uvcvideo, 480M
|__ Port 8: Dev 4, If 1, Class=Video, Driver=uvcvideo, 480M
/: Bus 01.Port 1: Dev 1, Class=root_hub, Driver=ehci-pci/3p, 480M
|__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/8p, 480M
$ sudo lsusb -d 05dc:a212 -vvv
Bus 003 Device 002: ID 05dc:a212 Lexar Media, Inc.
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 3.00
bDeviceClass 0 (Defined at Interface level)
bDeviceSubClass 0
bDeviceProtocol 0
bMaxPacketSize0 9
idVendor 0x05dc Lexar Media, Inc.
idProduct 0xa212
bcdDevice 1.00
iManufacturer 1 Lexar
iProduct 2 USB Flash Drive
iSerial 3 0C5E8B182D1D474C
bNumConfigurations 1
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 44
bNumInterfaces 1
bConfigurationValue 1
iConfiguration 0
bmAttributes 0x80
(Bus Powered)
MaxPower 224mA
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 2
bInterfaceClass 8 Mass Storage
bInterfaceSubClass 6 SCSI
bInterfaceProtocol 80 Bulk-Only
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0400 1x 1024 bytes
bInterval 0
bMaxBurst 3
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x02 EP 2 OUT
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0400 1x 1024 bytes
bInterval 0
bMaxBurst 3
Binary Object Store Descriptor:
bLength 5
bDescriptorType 15
wTotalLength 22
bNumDeviceCaps 2
USB 2.0 Extension Device Capability:
bLength 7
bDescriptorType 16
bDevCapabilityType 2
bmAttributes 0x00000006
Link Power Management (LPM) Supported
SuperSpeed USB Device Capability:
bLength 10
bDescriptorType 16
bDevCapabilityType 3
bmAttributes 0x00
wSpeedsSupported 0x000e
Device can operate at Full Speed (12Mbps)
Device can operate at High Speed (480Mbps)
Device can operate at SuperSpeed (5Gbps)
bFunctionalitySupport 2
Lowest fully-functional device speed is High Speed (480Mbps)
bU1DevExitLat 10 micro seconds
bU2DevExitLat 2047 micro seconds
Device Status: 0x000c
(Bus Powered)
U1 Enabled
U2 Enabled
Write speed with kernel 4.4:
$ sudo dd if=/dev/zero of=/dev/sdb bs=1M count=256
256+0 records in
256+0 records out
268435456 bytes (268 MB) copied, 5.98705 s, 44.8 MB/s
Write speed under Mac OS X:
$ sudo dd if=/dev/zero of=/dev/rdisk2 bs=1048576 count=256
256+0 records in
256+0 records out
268435456 bytes transferred in 0.941998 secs (284963933 bytes/sec)
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