On Fri 21-01-11 22:19:36, Tao Ma wrote: > On 01/21/2011 06:44 PM, Lukas Czerner wrote: > > Nice catch, do you plan to do the same for ext4 ? Btw, I do not think > > there is a need for new variable (free_count), you can as well do : > > > > free_blocks -= next - start; > > ... > > if (free_blocks < minblocks) > > break; > yeah, the extra varaible isn't needed. Here is the updated patch. > > Regards, > Tao > > Subject: [PATCH v2] ext3: speed up group trim with the right free block count. > From 48ab7651409df9b21dfaa9cec6a8db62467b8ca7 Mon Sep 17 00:00:00 2001 > From: Tao Ma <boyu.mt@xxxxxxxxxx> > Date: Fri, 21 Jan 2011 22:09:20 +0800 > Subject: [PATCH v2] ext3: speed up group trim with the right free block count. > > When we trim some free blocks in a group of ext3, we should > calculate the free blocks properly and check whether there are > enough freed blocks left for us to trim. Current solution will > only calculate free spaces if they are large for a trim which > is wrong. > > Let us see a small example: > a group has 1.5M free which are 300k, 300k, 300k, 300k, 300k. > And minblocks is 1M. With current solution, we have to iterate > the whole group since these 300k will never be subtracted from > 1.5M. But actually we should exit after we find the first 2 > free spaces since the left 3 chunks only sum up to 900K if we > subtract the first 600K although they can't be trimed. Thanks. Merged. Honza > > Cc: Jan Kara <jack@xxxxxxx> > Cc: Lukas Czerner <lczerner@xxxxxxxxxx> > Signed-off-by: Tao Ma <boyu.mt@xxxxxxxxxx> > --- > fs/ext3/balloc.c | 3 ++- > 1 files changed, 2 insertions(+), 1 deletions(-) > > diff --git a/fs/ext3/balloc.c b/fs/ext3/balloc.c > index 045995c..b9697f7 100644 > --- a/fs/ext3/balloc.c > +++ b/fs/ext3/balloc.c > @@ -1991,6 +1991,7 @@ ext3_grpblk_t ext3_trim_all_free(struct super_block *sb, unsigned int group, > spin_unlock(sb_bgl_lock(sbi, group)); > percpu_counter_sub(&sbi->s_freeblocks_counter, next - start); > > + free_blocks -= next - start; > /* Do not issue a TRIM on extents smaller than minblocks */ > if ((next - start) < minblocks) > goto free_extent; > @@ -2040,7 +2041,7 @@ free_extent: > cond_resched(); > > /* No more suitable extents */ > - if ((free_blocks - count) < minblocks) > + if (free_blocks < minblocks) > break; > } > > -- > 1.7.1 > -- Jan Kara <jack@xxxxxxx> SUSE Labs, CR -- 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
