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

root@192:~/flashbench# head /sys/block/mmcblk0/device/* 2>/dev/null | grep -v ^$ ==> /sys/block/mmcblk0/device/block <== ==> /sys/block/mmcblk0/device/cid <== 4134325344344742300000011200ba39 ==> /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 <== 0x000041 ==> /sys/block/mmcblk0/device/name <== SD4GB ==> /sys/block/mmcblk0/device/oemid <== 0x3432 ==> /sys/block/mmcblk0/device/power <== ==> /sys/block/mmcblk0/device/preferred_erase_size <== 4194304 ==> /sys/block/mmcblk0/device/scr <== 0235800001000000 ==> /sys/block/mmcblk0/device/serial <== 0x00000112 ==> /sys/block/mmcblk0/device/subsystem <== ==> /sys/block/mmcblk0/device/type <== SD ==> /sys/block/mmcblk0/device/uevent <== DRIVER=mmcblk MMC_TYPE=SD MMC_NAME=SD4GB MODALIAS=mmc:block

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

# Partition table used for tests:

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 2.06ms on 2.58ms post 2.09ms diff 505µs align 536870912 pre 1.97ms on 2.45ms post 1.97ms diff 481µs align 268435456 pre 2.03ms on 2.52ms post 2.03ms diff 486µs align 134217728 pre 2.06ms on 2.59ms post 2.03ms diff 542µs align 67108864 pre 2.07ms on 2.62ms post 2.04ms diff 561µs align 33554432 pre 2.06ms on 2.5ms post 2.07ms diff 436µs align 16777216 pre 2.08ms on 2.6ms post 2.05ms diff 538µs align 8388608 pre 2.1ms on 2.64ms post 2.03ms diff 576µs align 4194304 pre 2.05ms on 2.57ms post 2.08ms diff 504µs align 2097152 pre 1.97ms on 2.47ms post 1.99ms diff 493µs align 1048576 pre 1.97ms on 2.1ms post 1.99ms diff 117µs align 524288 pre 2ms on 2.06ms post 2ms diff 59.2µs align 262144 pre 2ms on 2.06ms post 1.99ms diff 60µs align 131072 pre 1.99ms on 2.06ms post 1.99ms diff 74.3µs align 65536 pre 2.02ms on 2.06ms post 1.98ms diff 57.1µs align 32768 pre 2ms on 2.06ms post 2ms diff 64.2µs align 16384 pre 1.98ms on 2.07ms post 1.98ms diff 88.2µs align 8192 pre 1.99ms on 2.06ms post 1.99ms diff 71µs align 4096 pre 2ms on 2.03ms post 1.99ms diff 32.1µs align 2048 pre 1.99ms on 2.03ms post 1.99ms diff 39.6µs

## 2MiB erase block ## Why the drop again at 1MiB? ## 8KiB page

andrew@bigbox:~/flashbench$ sudo ./flashbench /dev/sdc --open-au --erasesize=$[2*1024*1024] --blocksize=$[4*1024] --open-au-nr=1 2MiB 13M/s 1MiB 12.5M/s 512KiB 12.4M/s 256KiB 11.1M/s 128KiB 11.9M/s 64KiB 12.4M/s 32KiB 12.3M/s 16KiB 12.4M/s 8KiB 10.2M/s 4KiB 6.26M/s

andrew@bigbox:~/flashbench$ sudo ./flashbench /dev/sdc --open-au --erasesize=$[2*1024*1024] --blocksize=$[4*1024] --open-au-nr=2 2MiB 12.6M/s 1MiB 4.72M/s 512KiB 1.79M/s 256KiB 818K/s 128KiB 395K/s 64KiB 195K/s 32KiB 96.7K/s 16KiB 48.2K/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 13.2M/s 1MiB 6.02M/s 512KiB 4.8M/s 256KiB 1.39M/s 128KiB 725K/s 64KiB 315K/s 32KiB 148K/s 16KiB 80K/s 8KiB 39.5K/s 4KiB 19.6K/s

## Generally horrible at random

andrew@bigbox:~/flashbench$ sudo ./flashbench --findfat --fat-nr=6 /dev/sdc --blocksize=$[8*1024] --random 4MiB 2.58M/s 2.88M/s 6.1M/s 11.9M/s 11.3M/s 12.2M/s 2MiB 2.9M/s 2.73M/s 12.2M/s 11.6M/s 12.2M/s 12.4M/s 1MiB 2.58M/s 2.92M/s 4.72M/s 3.96M/s 3.9M/s 3.94M/s 512KiB 2.95M/s 2.62M/s 1.78M/s 1.33M/s 1.71M/s 1.72M/s 256KiB 1.74M/s 1.8M/s 934K/s 926K/s 925K/s 926K/s 128KiB 1.17M/s 1.19M/s 448K/s 447K/s 447K/s 448K/s 64KiB 743K/s 765K/s 213K/s 213K/s 213K/s 214K/s 32KiB 397K/s 410K/s 112K/s 113K/s 113K/s 113K/s