On 12/3/11, Eric Sandeen <sandeen@xxxxxxxxxx> wrote: > 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? BTW, bg_flags in struct ext4_group_desc is same as ext4_group_info's bb_state? Thank you, Kyungmin Park > > -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
