On Tuesday 22 February 2011, Wolfram Sang wrote: > # mount -t vfat /dev/mmcblk0p1 /mnt > # dd if=/mnt/test.dat of=/tmp/a bs=1024 > # umount /mnt > # ./dd --version > dd (coreutils) 8.5 In general, you should try to rule out file system, garbage collection, partitioning and cache effects. With coreutils dd, a good command is dd if=/dev/zero of=/dev/mmcblk0 bs=64K count=64 seek=256 oflag=direct * Always write multiples of 4 MB to avoid garbage collection * smaller block sizes may be faster, so writing 64 times 64K may be better than writing 4 MB once, depending on the card * don't write to the FAT area, so start writing at 16 MB into the device. * use direct I/O to bypass the page cache. * read from /dev/zero instead of a disk file to avoid measuring the wrong thing Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
