On 12/1/11 6:01 PM, Kyungmin Park wrote: > On 12/2/11, Eric Sandeen <sandeen@xxxxxxxxxx> wrote: >> On 12/1/11 1:00 AM, Kyungmin Park wrote: >>> From: Kyungmin Park <kyungmin.park@xxxxxxxxxxx> >>> >>> Now trim information doesn't stored at disk so every boot time. it's >>> cleared. >>> and do the trim all disk groups. >>> But assume that it's already trimmed at previous time so don't need to >>> trim it again. So set the intial state as trimmed. >>> >>> Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx> >>> --- >>> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c >>> index e2d8be8..97ef342 100644 >>> --- a/fs/ext4/mballoc.c >>> +++ b/fs/ext4/mballoc.c >>> @@ -1098,6 +1098,12 @@ int ext4_mb_init_group(struct super_block *sb, >>> ext4_group_t group) >>> goto err; >>> } >>> mark_page_accessed(page); >>> + >>> + /* >>> + * TRIM information is not stored at disk so set the initial >>> + * state as trimmed. Since previous time it's already trimmed all >>> + */ >>> + EXT4_MB_GRP_SET_TRIMMED(this_grp); >> > Hi, > >> Hm, so if there were freed but un-trimmed blocks at this point, we will >> never trim them until we free _another_ block in the group, right? That >> might be a reasonable tradeoff, but it is somewhat surprising behavior. >> >> i.e. say we do: >> >> mount /mnt >> rm -rf /mnt/very_big_file >> umount /mnt >> >> mount /mnt >> fitrim /mnt > another word, you can run fitrim after rm -rf > yes, it's trade-off. > > In my case, phone scenario, no umount system and data partition. it's > burden to trim at boot time. it has still slower boot time. > some daemon or program run fitrm at filesystem. it consumes time and > hurt other boot processes. >> >> then we won't trim anything at all, right, despite there being many >> new free blocks? Which would be rather unexpected. >> >> If we don't store the trimmed state on disk, I think we should >> probably stick with the slower first-time trim, and the more obvious >> behavior (all free blocks are always trimmed whenever a trim >> command is issued). > > Umm how do you think, introduce the trim force command for this? Alternately, can we use a bit in bg_flags to keep a better view of this state on disk, if this is critical? -Eric > Thank you, > Kyungmin Park -- 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
