On Wed, Jul 6, 2011 at 2:18 PM, Eric Sandeen <sandeen@xxxxxxxxxx> wrote: > On 7/6/11 3:47 PM, Dan Ehrenberg wrote: >> Previously, the stripe width was blindly used for determining the size >> of allocations. Now, the stripe width is used as a hint for the initial >> mb_group_prealloc; if it is greater than 1, then we make sure that >> mb_group_prealloc is some multiple of it, and otherwise it is ignored. >> mb_group_prealloc is always usable to adjust the preallocation strategy, >> not just when the stripe-width is 0 as before. >> >> Signed-off-by: Dan Ehrenberg <dehrenberg@xxxxxxxxxx> >> --- >> fs/ext4/mballoc.c | 40 +++++++++++++++++++++++++++++----------- >> 1 files changed, 29 insertions(+), 11 deletions(-) >> >> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c >> index 6ed859d..710c27f 100644 >> --- a/fs/ext4/mballoc.c >> +++ b/fs/ext4/mballoc.c >> @@ -127,13 +127,14 @@ >> * based on file size. This can be found in ext4_mb_normalize_request. If >> * we are doing a group prealloc we try to normalize the request to >> * sbi->s_mb_group_prealloc. Default value of s_mb_group_prealloc is >> - * 512 blocks. This can be tuned via >> - * /sys/fs/ext4/<partition/mb_group_prealloc. The value is represented in >> - * terms of number of blocks. If we have mounted the file system with -O >> + * 512 blocks. If we have mounted the file system with -O >> * stripe=<value> option the group prealloc request is normalized to the >> - * stripe value (sbi->s_stripe) >> + * the smallest multiple of the stripe value (sbi->s_stripe) which is >> + * greater than the default mb_group_prealloc. This can be tuned via >> + * /sys/fs/ext4/<partition>/mb_group_prealloc. The value is represented in >> + * terms of number of blocks. >> * >> - * The regular allocator(using the buddy cache) supports few tunables. >> + * The regular allocator (using the buddy cache) supports a few tunables. >> * >> * /sys/fs/ext4/<partition>/mb_min_to_scan >> * /sys/fs/ext4/<partition>/mb_max_to_scan >> @@ -2471,7 +2472,26 @@ int ext4_mb_init(struct super_block *sb, int needs_recovery) >> sbi->s_mb_stats = MB_DEFAULT_STATS; >> sbi->s_mb_stream_request = MB_DEFAULT_STREAM_THRESHOLD; >> sbi->s_mb_order2_reqs = MB_DEFAULT_ORDER2_REQS; >> + /* >> + * If the stripe width is 1, this makes no sense and >> + * we set it to 0 to turn off stripe handling code. >> + */ >> + if (sbi->s_stripe == 1) >> + sbi->s_stripe = 0; > > This strikes me as a weird band-aid-y place to fix this up. > > Wouldn't it be better suited for the option-parsing code, and/or > in ext4_get_stripe_size()? Why let a value of 1 get this far > only to override it here? > > -Eric The mount option parsing code wouldn't be a working place to do it, since it can be specified on-disk what the stripe size is. But ext4_get_stripe_size might be a good place to put it instead. I guess there are two unrelated parts to this patch: handling where the stripe width was set to 1, and handling where it's more than 1 but much less than what it should be. Dan Dan -- 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
