Currently, the maximum number of blocks in a block group is the number of bits in a block, since the block bitmap must be stored inside a single block. So on a 4 KB blocksize filesystem, the maximum number of blocks in a group is 32768. This constraint can limit the maximum size of the filesystem. Increasing the block group size allows also to reduce the number of groups in the filesystem. This patchset allows using several consecutive blocks to store the bitmaps, thus having larger block groups and so increasing the filesystem size. It applies against a linux-2.6.19-rc6 kernel and follows up the work on the 64-bit support done by Laurent Vivier and Alexandre Ratchov. These patches have been tested on a x86_64 machine with a 20TB device and with updated e2fsprogs available here: http://www.bullopensource.org/ext4/20061124 If we already see that the execution time of fsck and mkfs commands is reduced when increasing the size of groups on a large filesystem, I'll will do performance testing in the next days to see the other impacts of this modification. Any comments are welcome. Thanks, Valerie. - To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
