Re: [PATCH] Set the initial TRIM information as TRIMMED

Kyungmin Park
2011-12-01T08:39:07Z

On 12/1/11, Tao Ma <tm@tao.ma> wrote:
> On 12/01/2011 04:19 PM, Kyungmin Park wrote:
>> On 12/1/11, Tao Ma <tm@tao.ma> wrote:
>>> Hi Kyungmin,
>>> On 12/01/2011 03:00 PM, Kyungmin Park wrote:
>>>> From: Kyungmin Park <kyungmin.park@samsung.com>
>>>>
>>>> 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.
>>> sorry, I don't get your meaning here.
>>> Why can we assume that the group is already trimmed since it isn't
>>> stored in the disk?
>> To avoid the first time trim operation.
>> Every boot time. run the fitrim then it trims all block groups again.
>> but it's already done at previous time. so don't need to trim it
>> again.
>> Doesn't make sense? I think it's not designed behavior.
> You make the assumption that we run the fitrim every time at boot time.
> But what if the user don't run it at all? I guess "run fitrim during
> boot" is your firmware's behaviour and it isn't an assumption for all
> the other users.
>
> Having said that, this flag will be cleared whenever some
> blocks/clusters are freed. So maybe it doesn't matter for setting this
> flag during the group initialization.
Right,

I hope trim the real updated blocks only.

Thank you,
Kyungmin Park
>
> Thanks
> Tao
>>
>> In your patch at http://patchwork.ozlabs.org/patch/102918/
>>
>> with the patch:
>> [root@boyu-tm linux-2.6]# time ./ftrim /mnt/ext4/a
>> real 0m5.625s
>> user 0m0.000s
>> sys 0m1.269s
>> [root@boyu-tm linux-2.6]# time ./ftrim /mnt/ext4/a
>> real 0m0.002s
>> user 0m0.000s
>> sys 0m0.001s
>> [root@boyu-tm linux-2.6]# time ./ftrim /mnt/ext4/a
>> real 0m0.002s
>> user 0m0.000s
>> sys 0m0.001s
>>
>> After reboot. it maybe become below
>>
>> [root@boyu-tm linux-2.6]# time ./ftrim /mnt/ext4/a
>> real 0m0.002s
>> user 0m0.000s
>> sys 0m0.001s
>> [root@boyu-tm linux-2.6]# time ./ftrim /mnt/ext4/a
>> real 0m0.002s
>> user 0m0.000s
>> sys 0m0.001s
>> [root@boyu-tm linux-2.6]# time ./ftrim /mnt/ext4/a
>> real 0m0.002s
>> user 0m0.000s
>> sys 0m0.001s
>>
>> Thank you,
>> Kyungmin Park
>>>
>>> Thanks
>>> Tao
>>>>
>>>> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
>>>> ---
>>>> 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);
>>>> err:
>>>> ext4_mb_put_buddy_page_lock(&e4b);
>>>> return ret;
>>>
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