# BeagleBoard-xM is my only home computer with a built-in MMC device:

root@192:~# head /sys/block/mmcblk0/device/* 2>/dev/null | grep -v ^$ ==> /sys/block/mmcblk0/device/block <== ==> /sys/block/mmcblk0/device/cid <== 2750485344303447300119bad200ba7d ==> /sys/block/mmcblk0/device/csd <== 400e00325b5900001da77f800a40002d ==> /sys/block/mmcblk0/device/date <== 10/2011 ==> /sys/block/mmcblk0/device/driver <== ==> /sys/block/mmcblk0/device/erase_size <== 512 ==> /sys/block/mmcblk0/device/fwrev <== 0x0 ==> /sys/block/mmcblk0/device/hwrev <== 0x3 ==> /sys/block/mmcblk0/device/manfid <== 0x000027 ==> /sys/block/mmcblk0/device/name <== SD04G ==> /sys/block/mmcblk0/device/oemid <== 0x5048 ==> /sys/block/mmcblk0/device/power <== ==> /sys/block/mmcblk0/device/preferred_erase_size <== 4194304 ==> /sys/block/mmcblk0/device/scr <== 0235800001000000 ==> /sys/block/mmcblk0/device/serial <== 0x0119bad2 ==> /sys/block/mmcblk0/device/subsystem <== ==> /sys/block/mmcblk0/device/type <== SD ==> /sys/block/mmcblk0/device/uevent <== DRIVER=mmcblk MMC_TYPE=SD MMC_NAME=SD04G MODALIAS=mmc:block

# All further tests done using Transcend USB2.0 reader on my desktop

andrew@bigbox:~/flashbench$ sudo sfdisk -uS -l /dev/sdc

Disk /dev/sdc: 1898 cylinders, 128 heads, 32 sectors/track Units = sectors of 512 bytes, counting from 0

Device Boot Start End #sectors Id System /dev/sdc1 * 8192 7774207 7766016 c W95 FAT32 (LBA) /dev/sdc2 0 - 0 0 Empty /dev/sdc3 0 - 0 0 Empty /dev/sdc4 0 - 0 0 Empty

andrew@bigbox:~/flashbench$ sudo ./flashbench -a /dev/sdc --blocksize=1024 --count=100 align 1073741824 pre 2.1ms on 2.56ms post 2.07ms diff 475µs align 536870912 pre 1.96ms on 2.44ms post 1.97ms diff 479µs align 268435456 pre 2.01ms on 2.49ms post 2.01ms diff 482µs align 134217728 pre 2.09ms on 2.59ms post 2.03ms diff 529µs align 67108864 pre 2.05ms on 2.56ms post 1.99ms diff 536µs align 33554432 pre 2ms on 2.47ms post 2ms diff 465µs align 16777216 pre 2.02ms on 2.51ms post 2ms diff 502µs align 8388608 pre 2.03ms on 2.58ms post 2.02ms diff 552µs align 4194304 pre 1.93ms on 2.47ms post 1.99ms diff 508µs align 2097152 pre 1.94ms on 2.43ms post 1.96ms diff 484µs align 1048576 pre 1.96ms on 2.04ms post 1.94ms diff 89µs align 524288 pre 1.96ms on 2.01ms post 1.94ms diff 61.5µs align 262144 pre 1.94ms on 1.96ms post 1.93ms diff 24.4µs align 131072 pre 1.97ms on 2.03ms post 1.96ms diff 60.4µs align 65536 pre 1.95ms on 1.97ms post 1.93ms diff 28.7µs align 32768 pre 1.96ms on 2.03ms post 1.95ms diff 72.2µs align 16384 pre 1.94ms on 2.02ms post 1.94ms diff 79.1µs align 8192 pre 1.95ms on 2.04ms post 1.95ms diff 89.8µs align 4096 pre 1.94ms on 1.98ms post 1.95ms diff 37.2µs align 2048 pre 1.98ms on 2.01ms post 1.96ms diff 39µs

# 2MiB erase block # 8KiB pages

andrew@bigbox:~/flashbench$ sudo ./flashbench /dev/sdc --open-au --erasesize=$[2*1024*1024] --blocksize=$[4*1024] --open-au-nr=1 2MiB 12.9M/s 1MiB 12.6M/s 512KiB 12.2M/s 256KiB 11.7M/s 128KiB 12.3M/s 64KiB 12.5M/s 32KiB 12.3M/s 16KiB 12.3M/s 8KiB 9.98M/s 4KiB 6.36M/s

andrew@bigbox:~/flashbench$ sudo ./flashbench /dev/sdc --open-au --erasesize=$[2*1024*1024] --blocksize=$[4*1024] --open-au-nr=2 2MiB 12.7M/s 1MiB 4.84M/s 512KiB 1.79M/s 256KiB 815K/s 128KiB 393K/s 64KiB 194K/s 32KiB 96.3K/s 16KiB 48.4K/s 8KiB 24.1K/s 4KiB 12K/s

andrew@bigbox:~/flashbench$ sudo ./flashbench /dev/sdc --open-au --erasesize=$[2*1024*1024] --blocksize=$[4*1024] --open-au-nr=1 --random 2MiB 6.24M/s 1MiB 5.79M/s 512KiB 4.82M/s 256KiB 1.41M/s 128KiB 713K/s 64KiB 312K/s 32KiB 147K/s 16KiB 79.4K/s 8KiB 39.1K/s 4KiB 182K/s

andrew@bigbox:~/flashbench$ sudo ./flashbench /dev/sdc --open-au --erasesize=$*1024*1024] --blocksize=$[4*1024] --open-au-nr=2 --random 2MiB 5.44M/s 1MiB 4.26M/s 512KiB 1.72M/s 256KiB 798K/s 128KiB 386K/s 64KiB 191K/s time_write: Input/output error 32KiB 96.7K/s time_write: Input/output error 16KiB 47.9K/s 8KiB 24K/s 4KiB 182K/s