linux-kernel - Re: [PATCH 3/3] f2fs: provide more chance for node and data to get ssr segment

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Date:   Fri, 24 Feb 2017 19:41:03 +0800
From:   Yunlong Song <yunlong.song@...wei.com>
To:     Chao Yu <yuchao0@...wei.com>, Jaegeuk Kim <jaegeuk@...nel.org>
CC:     <chao@...nel.org>, <sylinux@....com>, <miaoxie@...wei.com>,
        <bintian.wang@...wei.com>, <linux-fsdevel@...r.kernel.org>,
        <linux-f2fs-devel@...ts.sourceforge.net>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/3] f2fs: provide more chance for node and data to get
 ssr segment

Hi, Chao,

Not looks good to me, since there is some case your code does not include:
if type is CURSEG_HOT_DATA, and if get_victim also returns 0 for both CURSEG_HOT_DATA and
CURSEG_WARM_DATA, then i will be -1 and pass to get_victim in your code.  So I still suggest
my original patch attached below.

On 2017/2/24 18:47, Chao Yu wrote:
> On 2017/2/24 17:19, Yunlong Song wrote:
>> Hi Jaegeuk and Chao,
>>
>>     How about the question I pointed out in last mail:
>>     Why not take "neighboring temperature" for ssr? For example, if type == CURSEG_COLD_DATA,
>>     the new patch selects CURSEG_HOT_DATA first, why not select CURSEG_WARM_DATA first?
>>     The patch I sent ensure this "neighboring temperature" for ssr. This is to reduce the influence of
>>     mixing different levels of hot/code node types.
> Agreed, I sent one patch for changing the policy of SSR, how do you think of it?
>
> Thanks,
>
>> On 2017/2/24 17:05, Chao Yu wrote:
>>> Hi Jaegeuk,
>>>
>>> Reviewed-by: Chao Yu <yuchao0@...wei.com>
>>>
>>> For your attached two patches.
>>>
>>> Thanks,
>>>
>>> On 2017/2/23 9:17, Jaegeuk Kim wrote:
>>>> Hi Yunlong,
>>>>
>>>> I've been testing the similar patches as I attached.
>>>>
>>>> Thanks,
>>>>
>>>> On 02/22, Yunlong Song wrote:
>>>>> Signed-off-by: Yunlong Song <yunlong.song@...wei.com>
>>>>> ---
>>>>>  fs/f2fs/segment.c | 9 +++++++++
>>>>>  1 file changed, 9 insertions(+)
>>>>>
>>>>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
>>>>> index 9d13743..5fe71b9 100644
>>>>> --- a/fs/f2fs/segment.c
>>>>> +++ b/fs/f2fs/segment.c
>>>>> @@ -1540,12 +1540,17 @@ static int get_ssr_segment(struct f2fs_sb_info *sbi, int type)
>>>>>  {
>>>>>  	struct curseg_info *curseg = CURSEG_I(sbi, type);
>>>>>  	const struct victim_selection *v_ops = DIRTY_I(sbi)->v_ops;
>>>>> +	int old_type = type;
>>>>>  
>>>>>  	if (IS_NODESEG(type)) {
>>>>>  		for (; type >= CURSEG_HOT_NODE; type--)
>>>>>  			if (v_ops->get_victim(sbi, &(curseg)->next_segno,
>>>>>  							BG_GC, type, SSR))
>>>>>  				return 1;
>>>>> +		for (type = old_type + 1; type <= CURSEG_COLD_NODE; type++)
>>>>> +			if (v_ops->get_victim(sbi, &(curseg)->next_segno,
>>>>> +							BG_GC, type, SSR))
>>>>> +				return 1;
>>>>>  		return 0;
>>>>>  	}
>>>>>  
>>>>> @@ -1554,6 +1559,10 @@ static int get_ssr_segment(struct f2fs_sb_info *sbi, int type)
>>>>>  		if (v_ops->get_victim(sbi, &(curseg)->next_segno,
>>>>>  						BG_GC, type, SSR))
>>>>>  			return 1;
>>>>> +	for (type = old_type + 1; type <= CURSEG_COLD_DATA; type++)
>>>>> +		if (v_ops->get_victim(sbi, &(curseg)->next_segno,
>>>>> +						BG_GC, type, SSR))
>>>>> +			return 1;
>>>>>  	return 0;
>>>>>  }
>>>>>  
>>>>> -- 
>>>>> 1.8.5.2
>>> .
>>>
>>
>
> .
>


-- 
Thanks,
Yunlong Song