Memory Technology Devices (MTD)

The Memory Technology Devices (MTD) layer in the kernel is used to provide an abstraction layer for memory devices (most often, flash devices). This allows higher levels (such as filesystems like jffs or yaffs) to not care about the physical backing. It could be on a parallel NOR flash chip hooked up to the asynchronous memory bus, or a serial flash chip on the SPI bus, or a NAND flash chip hooked up a variety of ways.

The MTD homepage can be found at http://www.linux-mtd.infradead.org/.

There are a couple of layers in the MTD stack that you should be familiar with:

• Chip driver (the chip-specific protocol/command set/instructions/etc…)
• Mapping driver (how the chip is connected to the processor)
• Partition layout (division and properties for sections of the chip)
• Block/Character interface (how userspace accesses things directly)
• Flash file systems

As you get lower down closer to the hardware, some pieces may be integrated or split out further. Unless you're writing a driver for a new chip, most things will be done “for you” already.

Many flash devices are already supported by the Linux kernel. To use any of them, you'll need these common options in your kernel configuration.

Device Drivers  --->
  Memory Technology Devices (MTD)  --->
    <*> Memory Technology Device (MTD) support
    [*]   Direct char device access to MTD devices
    [*]   Caching block device access to MTD devices

All options here are found under the MTD menu. The parent nodes have been omitted for brevity. Keep in mind that there is no restriction on using different flash types simultaneously (parallel and SPI and NAND and …).

Also keep in mind that these options only turn on drivers. They do not include the other half of the equation: board resources. Your board will have to declare appropriate resources in your Board Resources file. Consult other boards (such as the BF537-STAMP or BF548-EZKIT) for good examples.

Has a full address/data (memory) interface that allows random access to any location. It is block-erasable (many words will be erased at once), but is typically programmable as words or bytes at a time. Typically connected via the asynchronous memory bus.

To use this type of flash under Linux, you probably want these options:

RAM/ROM/Flash chip drivers  --->
  <*> Detect flash chips by Common Flash Interface (CFI) probe
  <*> Support for Intel/Sharp flash chips
  <*> Support for AMD/Fujitsu flash chips
  <*> Support for RAM chips in bus mapping
  <*> Support for ROM chips in bus mapping

Mapping drivers for chip access  --->
  <*> CFI Flash device in physical memory map
         (the address/length options are ignored)
  < > Generic uClinux RAM/ROM filesystem support

When the latter option is enabled, you'd get an extra ROMFS partition as mtdblock0. This may force an ext2 over INITRAMFS image upon make.

For the BF533-STAMP, you will also need:

Mapping drivers for chip access  --->
  [*] Support non-linear mappings of flash chips
  <*> Blackfin BF533-STAMP Flash Chip Support
  (0x7BB0) EBIU_AMBCTL For Flash (Bank 0)
  (0x7BB0) EBIU_AMBCTL For Flash (Bank 1)
  (0x7BB0) EBIU_AMBCTL For Flash (Bank 2)
  (0x7BB0) EBIU_AMBCTL For Flash (Bank 3)

For flash parts that also need some GPIOs to assist in addressing, you will want this driver:

Mapping drivers for chip access  --->
  [*] Support non-linear mappings of flash chips
  <*> GPIO-assisted Flash Chip Support

You will need some platform resources declared for this driver. See arch/blackfin/mach-bf537/boards/cm_bf537.c for an example.

A SPI-compatible interface as used for serial EEPROMs which provides a sequential read access. Densities tend to be higher, but access times are slower.

To use this type of flash under Linux, you probably want these options:

Mapping drivers for chip access  --->
  [*] Support non-linear mappings of flash chips
  < > Generic uClinux RAM/ROM filesystem support (disable this option)
Self-contained MTD device drivers  --->
  <*> Support most SPI Flash chips (AT26DF, M25P, W25X, ...)

The ideal solution for applications requiring a large amount of data storage memory. The common densities are much larger such as sizes from 128Mbit (16Mbytes) to 8Gbit (1Gbyte), but requires bad block handling. May be connected via the asynchronous memory bus or a dedicated controller.

To use this type of flash under Linux, you probably want one of these options:

NAND Device Support  --->
  <*> NAND Flash device for BF537 STAMP board
  <*> Blackfin on-chip NAND Flash Controller driver
  [*]   BF5XX NAND Hardware ECC
  <*> Support for generic platform NAND driver

Since each flash chip vendor designs their own communications protocol (for telling the chip to read/write/erase/protect regions of the flash), all of this logic is hidden away at the chip driver level. This presents to the next MTD layer a simple abstract interface of common operations. Higher levels can then write to this common interface and so work with a variety of flash chips without needing to change anything.

Nowadays, flash technologies in the same field tend to support the same instruction set (for example, CFI on parallel NOR flashes). This allows the same software chip driver to support a wide variety of arbitrary flash chips. You should, however, verify that the flash chip you're planning on using is actively supported before designing it into your board.

This also means that, unless you ignore the aforementioned advice, you probably will not need to write your own chip driver for an exotic flash part.

A mapping driver is used as the “glue” driver. It is used to manage how the flash device is actually hooked up to the processor. In other words, it facilitates communication between the Blackfin and the flash chip, but it does not know anything about the actual communication (since that is the job of the chip driver). This feature tends to be specific to parallel flash chips however. You could consider the SPI bus the “mapping driver” for serial NOR flashes, but you need not worry about that layer as there is a common SPI framework. NAND devices tend to be very board specific already, so each driver provides its own method/degree of board customization.

The mapping driver is also how the partition layout is tied to a specific device, but more on that in the next section.

One of the common (and simplest) mapping drivers is the physical mapping driver (physmap). This driver is used for any CFI compliant flash which is completely directly addressable on the memory bus. For example, if an asynchronous memory bank is dedicated to a flash chip and you can access it without any other assistance, this common mapping driver would be used.

Some examples of when a custom mapping driver will be needed:

• flash and another device (like ethernet on the BF533-STAMP) share a single asynchronous bank
• flash uses GPIO's for additional addressing

The mapping driver allows you to hook every flash operation before calling down into the specific chip driver.

All mapping drivers are stored in the same location in linux-2.6.x/drivers/mtd/maps/. This may seem like an odd place for such a (usually) board-specific option, but it is how things are done. It also allows for mapping drivers which do very similar operations to be unified for multiple boards/architectures.

Often times, people do not want to use a flash device as just one big chunk of contiguous storage. Perhaps you want to store the bootloader, a kernel, a root filesystem, and reserve a small chunk for your own product-specific purpose. By defining a partition layout, you need not manage the storage yourself. The kernel will break up and enforce the specified boundaries for you. If you wanted, you could even mark some partitions with custom attributes (such as making a recovery partition as read-only).

Since this topic tends to be much easier to just copy and paste existing examples, please see the Board Examples section below.

While the MTD framework does sufficiently abstract the lower layers to allow you to format and use any file system type on flash media, you should only be using “flash friendly” file systems on them. Since flash media presents unique restrictions when compared to standard media (flash must be erased before writing, you have to erase/write in chunks rather than just bytes, limited number of erase/write cycles before flash goes bad, etc…), you should use a file system that is designed to work with these things in mind. Otherwise you risk arbitrary file system corruption or worse, premature flash failure.

Certainly any read-only file system (such as romfs or cramfs) would be OK as you only write it once, but if you want persistent backing (in other words, a writable file system), then you currently have two choices: jffs and yaffs. See the respective pages for more information on each type.

Not all boards will be shown, just a representative sampling. Keep in mind that the structures documented here are not the entire picture. The resources are often declared in a couple of related structures. Consult the relevant board resources file for the full picture.

For most devices, you can declare a partition table in a couple of ways:

• Command line partition table parsing
• board resources file via relevant partition structure
• a custom mtd_part_parser (not discussed here)

The command line partition support is controlled via a kernel configuration option:

Device Drivers  --->
  Memory Technology Devices (MTD)  --->
    <*> Memory Technology Device (MTD) support
    [*]   MTD partitioning support
    [*]     Command line partition table parsing

Assuming you've enabled the kernel configuration option, you can override the default layout that is in the board resources by using the kernel command line. For example:

bootargs=mtdparts=FLASH-DRIVER:256k(uboot)ro,1792k(kernel),-(rootfs)

Replace the FLASH-DRIVER with whatever driver you are using. For the BF533-STAMP parallel flash, this will be bfin-async-flash. For the default physical mapping driver, this will be physmap-flash.0 (increment the number for each flash). For SPI flashes, replace with the driver name (such as m25p80 -- this is the driver name, not the type).

For the full command line syntax, consult the linux-2.6.x/drivers/mtd/cmdlinepart.c file. It will be documented at the top.

There are optional flags which can be set for each partition. The variable mask_flags can be set to (from linux-2.6.x/include/mtd/mtd-abi.h):

• MTD_CAP_ROM - No write
• MTD_CAP_RAM - Bits can be cleared, Bits can be set, Direct I/O is possible
• MTD_CAP_NORFLASH - Bits can be cleared, Has an erase function
• MTD_CAP_NANDFLASH - Bits can be cleared, Has an erase function, Out-of-band data

Assuming everything works out, you should see messages from the kernel about creating MTD partitions. The exact output is dependent on your partition table, but you should be able to gloss the details.

Here we see three partitions being setup for the parallel NOR flash (declared via the command line), two partitions for the SPI flash (declared via the board resources), and two partitions for the NAND flash (declared via the board resources).

3 cmdlinepart partitions found on MTD device physmap-flash.0
Creating 3 MTD partitions on "physmap-flash.0":
0x00000000-0x00040000 : "uboot"
0x00040000-0x00200000 : "kernel"
0x00200000-0x02000000 : "rootfs"
m25p80 spi0.1: m25p16 (2048 Kbytes)
Creating 2 MTD partitions on "m25p80":
0x00000000-0x00040000 : "bootloader"
0x00040000-0x00100000 : "linux kernel"
Creating 2 MTD partitions on "NAND 256MiB 3,3V 8-bit":
0x00000000-0x00400000 : "Linux Kernel"
0x00400000-0x10000000 : "File System"

Pretty much all ADI boards use the Physical Mapping driver (physmap) to connect CFI compliant parallel NOR flashes. The only exceptions are the BF533-EZKit and BF533-STAMP.

This board has a non-CFI compliant flash which is unlikely to be used by customers in production. Please refer to other boards for examples applicable to your setup.

This board uses the bfin-async-flash mapping driver to allow simultaneous access of the flash and ethernet on the same asynchronous memory bank.

static struct mtd_partition stamp_partitions[] = {
	{
		.name   = "bootloader(nor)",
		.size   = 0x40000,
		.offset = 0,
	}, {
		.name   = "linux kernel(nor)",
		.size   = 0x180000,
		.offset = MTDPART_OFS_APPEND,
	}, {
		.name   = "file system(nor)",
		.size   = MTDPART_SIZ_FULL,
		.offset = MTDPART_OFS_APPEND,
	}
};

The SPI resources (such as SPI chip select, DMA, byte-size, etc…) are declared like a normal SPI device. You can find information on this in the SPI document.

You could hook up a NAND flash via the asynchronous memory bank. We've created and documented such an example cf-ide-nand board. For Blackfins that include an on-chip NAND flash controller, you can just use that.

A package called mtd-utils exists for managing all flash devices (such as erasing/dumping/testing). Please see the mtd-utils page for more information.

Additionally, each file system type (jffs and yaffs) includes its own set of utilities. Please consult each page for file system specific information.

Here we test performance of MTD devices using bonnie, with different I/O scheduler policies.

• System Setting

• MTD Setting

physmap platform flash device: 02000000 at 20000000
physmap-flash.0: Found 1 x16 devices at 0x0 in 16-bit bank
physmap-flash.0: Found an alias at 0x1000000 for the chip at 0x0
 Intel/Sharp Extended Query Table at 0x010A
 Intel/Sharp Extended Query Table at 0x010A
 Intel/Sharp Extended Query Table at 0x010A
 Intel/Sharp Extended Query Table at 0x010A
 Intel/Sharp Extended Query Table at 0x010A
Using buffer write method
Using auto-unlock on power-up/resume
cfi_cmdset_0001: Erase suspend on write enabled
erase region 0: offset=0x0,size=0x20000,blocks=127
erase region 1: offset=0xfe0000,size=0x8000,blocks=4
RedBoot partition parsing not available
Using physmap partition information
Creating 3 MTD partitions on "physmap-flash.0":
0x00000000-0x00040000 : "bootloader(nor)"
0x00040000-0x00440000 : "linux kernel(nor)"
0x00440000-0x01000000 : "file system(nor)"

BF5xx on-chip NAND FLash Controller Driver, Version 1.2 (c) 2007 Analog Devices, Inc.

bf5xx-nand bf5xx-nand.0: page_size=256, data_width=8, wr_dly=3, rd_dly=3
NAND device: Manufacturer ID: 0x20, Chip ID: 0xda (ST Micro NAND 256MiB 3,3V 8-bit)
Creating 2 MTD partitions on "NAND 256MiB 3,3V 8-bit":
0x00000000-0x00400000 : "linux kernel(nand)"
0x00400000-0x10000000 : "file system(nand)"

m25p80 spi0.1: m25p16 (2048 Kbytes)
Creating 2 MTD partitions on "m25p80":
0x00000000-0x00040000 : "bootloader(spi)"
0x00040000-0x00200000 : "linux kernel(spi)"
bfin-spi bfin-spi.0: Blackfin on-chip SPI Controller Driver, Version 1.0, regs_base@ffc00500, dma channel@4
bfin-spi bfin-spi.1: Blackfin on-chip SPI Controller Driver, Version 1.0, regs_base@ffc02300, dma channel@5

root:/> cat /proc/mtd 
dev:    size   erasesize  name
mtd0: 00040000 00020000 "bootloader(nor)"
mtd1: 00400000 00020000 "linux kernel(nor)"
mtd2: 00bc0000 00020000 "file system(nor)"
mtd3: 00400000 00020000 "linux kernel(nand)"
mtd4: 0fc00000 00020000 "file system(nand)"
mtd5: 00040000 00010000 "bootloader(spi)"
mtd6: 001c0000 00010000 "linux kernel(spi)"

root:/> echo "noop" > /sys/block/mtdblock4/queue/scheduler
root:/> cat /sys/block/mtdblock4/queue/scheduler                                
[noop] anticipatory cfq                                                         
root:/> mount -t jffs2 /dev/mtdblock4 /mnt/                                     
root:/> bonnie++ -u root -d /mnt/  

• Result:

Version  1.94       ------Sequential Output------ --Sequential Input- --Random- 
Concurrency   1     -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks-- 
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP 
blackfin       300M     8  66  3114  91  3183  91   183  99 13805  75 943.3  84 
Latency              2439ms     644ms     648ms   83999us     648ms     448ms   
Version  1.94       ------Sequential Create------ --------Random Create-------- 
blackfin            -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete-- 
              files  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP 
                 16   462  94  7599 100   493  93   542  98  8846  98   582  98 
Latency             59999us    4000us   48000us   43999us    4000us   44000us

root:/> umount /mnt/ 
root:/> cat /sys/block/mtdblock4/queue/scheduler                                
noop anticipatory [cfq]                                                             
root:/> mount -t jffs2 /dev/mtdblock4 /mnt/                                     
root:/> bonnie++ -u root -d /mnt/   

• Result:

Version  1.94       ------Sequential Output------ --Sequential Input- --Random- 
Concurrency   1     -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks-- 
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP 
blackfin       300M     8  69  3113  91  3188  91   184  99 13714  74 939.0  83 
Latency              2168ms     644ms     667ms     123ms     648ms     447ms   
Version  1.94       ------Sequential Create------ --------Random Create-------- 
blackfin            -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete-- 
              files  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP 
                 16   465  93  7627  99   522  98   547  98  9022  99   588  99 
Latency             60000us    4000us   40000us   40000us    4000us   40000us 

root:/> umount /mnt/ 
root:/> cat /sys/block/mtdblock4/queue/scheduler                                
noop anticipatory [cfq]                                                             
root:/> mount -t jffs2 /dev/mtdblock4 /mnt/                                     
root:/> bonnie++ -u root -p 2
root:/> bonnie++ -u root -y s > out1 &
root:/> bonnie++ -u root -y s > out2 &

• Result:

root:/> cat out1 
Version  1.94       ------Sequential Output------ --Sequential Input- --Random-
Concurrency   1     -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP
blackfin       300M     4  32  1194  46  1213  47    91  49  7744  45 404.1  42
Latency              3988ms     687ms     503ms     147ms     448ms     471ms
Version  1.94       ------Sequential Create------ --------Random Create--------
blackfin            -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
              files  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP
                 16   260  48  2582  50   284  49   274  49  4546  50   297  49
Latency             68000us   24000us     324ms   47999us   27999us   52000us

root:/> cat out2 
Version  1.94       ------Sequential Output------ --Sequential Input- --Random-
Concurrency   1     -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP
blackfin       300M     4  32  1174  47  1207  48    90  50  7677  47 404.0  42
Latency              3780ms     700ms     456ms     140ms     448ms     467ms
Version  1.94       ------Sequential Create------ --------Random Create--------
blackfin            -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
              files  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP
                 16   255  46  1934  61   281  48   275  49  4481  49   292  50
Latency             64000us   27999us     332ms   47999us   27999us   52000us

root:/> umount /mnt/ 
root:/> cat /sys/block/mtdblock4/queue/scheduler                                
[noop] anticipatory cfq                                                             
root:/> mount -t jffs2 /dev/mtdblock4 /mnt/                                     
root:/> bonnie++ -u root -p 2
root:/> bonnie++ -u root -y s > out1 &
root:/> bonnie++ -u root -y s > out2 &

• Result:

root:/> cat out1                                                                
Version  1.94       ------Sequential Output------ --Sequential Input- --Random- 
Concurrency   1     -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks-- 
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP 
blackfin       300M     4  33  1170  48  1208  48    89  49  7937  45 403.0  43 
Latency              4060ms     711ms     471ms     175ms     456ms     523ms   
Version  1.94       ------Sequential Create------ --------Random Create-------- 
blackfin            -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete-- 
              files  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP 
                 16   244  46  3810  50   282  50   261  48  4394  51   285  49 
Latency             76000us   36000us   59999us   71999us   31999us   52000us   

root:/> cat out2                                                                
Version  1.94       ------Sequential Output------ --Sequential Input- --Random- 
Concurrency   1     -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks-- 
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP 
blackfin       300M     4  34  1190  48  1206  47    89  49  8074  46 403.3  42 
Latency              4188ms     652ms     467ms     171ms     452ms     532ms   
Version  1.94       ------Sequential Create------ --------Random Create-------- 
blackfin            -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete-- 
              files  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP 
                 16   245  46  3817  50   286  49   261  48  4409  49   280  49 
Latency             76000us   35999us   51999us   67999us   35999us   51999us   

root:/> umount /mnt/ 
root:/> cat /sys/block/mtdblock4/queue/scheduler                                
noop [anticipatory] cfq                                                             
root:/> mount -t jffs2 /dev/mtdblock4 /mnt/                                     
root:/> bonnie++ -u root -p 2
root:/> bonnie++ -u root -y s > out1 &
root:/> bonnie++ -u root -y s > out2 &

• Result:

root:/> cat out1 
Version  1.94       ------Sequential Output------ --Sequential Input- --Random-
Concurrency   1     -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP
blackfin       300M     4  33  1175  47  1205  47    89  49  7841  45 403.9  41
Latency              3739ms     672ms     495ms     148ms     644ms     484ms
Version  1.94       ------Sequential Create------ --------Random Create--------
blackfin            -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
              files  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP
                 16   248  46  3828  50   286  50   270  49  4535  50   284  48
Latency             80000us   35999us   56000us   43999us   28000us   56000us

root:/> cat out2
Version  1.94       ------Sequential Output------ --Sequential Input- --Random-
Concurrency   1     -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP
blackfin       300M     4  33  1171  47  1207  47    89  49  8198  47 402.8  43
Latency              3819ms     679ms     504ms     128ms     456ms     551ms
Version  1.94       ------Sequential Create------ --------Random Create--------
blackfin            -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
              files  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP
                 16   248  46  3799  50   283  48   271  49  4481  49   289  49
Latency             64000us   35999us   60000us   51999us   35999us   48000us 

root:/> echo "noop" > /sys/block/mtdblock4/queue/scheduler                      
root:/> cat /sys/block/mtdblock4/queue/scheduler                                
[noop] anticipatory cfq                                                         
root:/> flash_eraseall /dev/mtd4                                 
root:/> mount -t yaffs2 /dev/mtdblock4 /mnt/                                            
root:/> bonnie++ -u root -d /mnt -s 200M                                        

• Result

                                               
Version  1.94       ------Sequential Output------ --Sequential Input- --Random- 
Concurrency   1     -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks-- 
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP 
blackfin       200M    49  99  3598  66  2005  60   181  98  5408  46 373.2  76 
Latency               164ms     644ms     672ms   64000us     663ms     459ms   
Version  1.94       ------Sequential Create------ --------Random Create-------- 
blackfin            -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete-- 
              files  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP 
                 16   108  97  3957  77   475  60   107  97  6918  99   242  80 
Latency             24000us   16000us   19999us   20000us    4000us   23999us  

root:/> echo "noop" > /sys/block/mtdblock2/queue/scheduler                      
root:/> cat /sys/block/mtdblock2/queue/scheduler                                
[noop] anticipatory cfq                                                         
root:/> mount -t jffs2 /dev/mtdblock2 /mnt/                                     
root:/> bonnie++ -u root -d /mnt -n 0 -f 

• Result:

Version  1.94       ------Sequential Output------ --Sequential Input- --Random- 
Concurrency   1     -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks-- 
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP 
blackfin       300M            1857  97   604  99           13578  78  43.1  99 
Latency                         652ms     463ms               652ms     483ms  

root:/> cat /sys/block/mtdblock2/queue/scheduler                                
noop [anticipatory] cfq                                   
root:/> bonnie++ -u root -d /mnt -n 0 -f 

• Result:

Version  1.94       ------Sequential Output------ --Sequential Input- --Random- 
Concurrency   1     -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks-- 
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP 
blackfin       300M            1817  97   608  99           13928  78  43.3  99 
Latency                         652ms     463ms               648ms     580ms  

                                    
root:/> echo "cfq" > /sys/block/mtdblock2/queue/scheduler                       
root:/> cat /sys/block/mtdblock2/queue/scheduler                                
noop anticipatory [cfq]                                                         
root:/> umount /mnt/                                                            
root:/> mount -t jffs2 /dev/mtdblock2 /mnt/                                     
root:/> bonnie++ -u root -d /mnt -n 0 -f 

• Result:

Version  1.94       ------Sequential Output------ --Sequential Input- --Random- 
Concurrency   1     -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks-- 
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP 
blackfin       300M            1847  97   610  99           13516  78  44.0  99 
Latency                         652ms     468ms               652ms     568ms   

root:/> bonnie++ -u root -d /mnt -f -n 0 -s 40M

• Result:

Version  1.94       ------Sequential Output------ --Sequential Input- --Random- 
Concurrency   1     -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks-- 
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP 
blackfin        40M            1607  69  1012  57           70620 100 548.9  57 
Latency                       11999us    1359ms              4000us   96000us  

root:/> bonnie++ -u root -d /mnt -f -n 0 -s 40M

• Result:

Version  1.94       ------Sequential Output------ --Sequential Input- --Random- 
Concurrency   1     -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks-- 
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP 
blackfin        40M            1608  70   976  55           62439  99 467.7  53 
Latency                       11999us    1292ms              4000us   79999us  

root:/> bonnie++ -u root -d /mnt -f -n 0 -s 40M

• Result:

Version  1.94       ------Sequential Output------ --Sequential Input- --Random- 
Concurrency   1     -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks-- 
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP 
blackfin        40M            1615  69   979  55           66064  94 374.2  45 
Latency                        8000us    1359ms              7999us   76000us  

Note The Input speed may be invalid. Since there is only 2MB SPI flash on BF548-Ezkit, the file size cannot be very large. According to bonnie++, file size should double RAM size in order to get a good result.

Output: 1.5 MB/s, Input: 6.7 MB/s

root:/> mount -t jffs2 /dev/mtdblock6 /mnt/
root:/> time dd conv=fsync if=/dev/zero of=/mnt/10m.bin bs=1M count=10
10+0 records in
10+0 records out
real    0m 6.46s
user    0m 0.00s
sys     0m 4.53s
root:/> umount /mnt/
root:/> mount -t jffs2 /dev/mtdblock6 /mnt/
root:/> time cp /mnt/10m.bin /var/
real    0m 1.49s
user    0m 0.02s
sys     0m 0.91s

• System Setting

• Result

Comparing the sequential output/input result, we can see HW ECC has performance advantage over SW ECC.

root:/> bonnie++ -u root -d /mnt/
Version  1.94       ------Sequential Output------ --Sequential Input- --Random-
Concurrency   1     -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP
blackfin       300M     5  24  1023  91  1032  90   207  99  7704  75 341.4  43
Latency              2364ms   84000us     131ms   51999us     652ms     527ms
Version  1.94       ------Sequential Create------ --------Random Create--------
blackfin            -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
              files  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP
                 16   260  91  6150 100   279  95   278  93  7728  99   278  96
Latency             71999us    8000us   47999us   52000us    4000us   43999us

root:/> bonnie++ -u root -d /mnt/
Version  1.94       ------Sequential Output------ --Sequential Input- --Random-
Concurrency   1     -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP
blackfin       300M     7  66   994  97  1024  97   202  99  5787  91 483.8  99
Latency              2080ms   43999us   75999us     119ms     655ms     492ms
Version  1.94       ------Sequential Create------ --------Random Create--------
blackfin            -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
              files  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP
                 16   266  92  5979 100   297  99   274  97  7515 100   292  99
Latency             43999us    8000us   43999us   43999us    4000us   52000us