On Fri, Jan 11, 2008 at 03:04:08PM +0100, Valerie Clement wrote: > Hi, > > I've got problems with mballoc when I create the ext4 filesystem with > the "uninit_groups" option enabled. > > First, I do a single test on a filesystem created without the > "uninit_groups" option and mounted with the defaults option: > dd if=/dev/zero of=/mnt/test/foo bs=1M count=1024 > > In this case, the file blocks are allocated in the groups 4, 5, 6, 7, 8, > 9, 10. > > When the filesystem is created with the "uninit_groups" option enabled > and mounted with the defaults option, I do the same dd command. > > In this case, the file blocks are allocated in the groups 5, 7, 9, 25, > 27, 49, 81. It seems that the blocks could be allocated only in the > already initialized groups. > That is because we skip the uninitialized group in ext4_mb_good_group. I guess we are trying criteria 0 allocation and we skip uninit group for criteria 0 . You can tune by setting higher value for /proc/fs/ext4/partition/orders2_req. Setting it to a high value would skip criteria 0 allocation for small requests. I guess you are using delayed allocation ? -aneesh - 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
