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Subject: Re: [PATCH 3/3] f2fs: export migration_granularity sysfs entry
To:     Yunlong Song <yunlong.song@huawei.com>, <jaegeuk@kernel.org>
CC:     <linux-f2fs-devel@lists.sourceforge.net>,
        <linux-kernel@vger.kernel.org>, <chao@kernel.org>
References: <20181024103728.9870-1-yuchao0@huawei.com>
 <20181024103728.9870-3-yuchao0@huawei.com>
 <a85b83ee-affb-138b-f804-0590eb2cd3be@huawei.com>
From:   Chao Yu <yuchao0@huawei.com>
Message-ID: <d3931432-2add-1c46-9eb4-8b88ac903c67@huawei.com>
Date:   Thu, 25 Oct 2018 14:10:03 +0800
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On 2018/10/25 11:01, Yunlong Song wrote:
> 
> 
> On 2018/10/24 18:37, Chao Yu wrote:
>> Add one sysfs entry to control migration granularity of GC in large
>> section f2fs, it can be tuned to mitigate heavy overhead of migrating
>> huge number of blocks in large section.
>>
>> Signed-off-by: Chao Yu <yuchao0@huawei.com>
>> ---
>>   Documentation/ABI/testing/sysfs-fs-f2fs | 9 +++++++++
>>   fs/f2fs/sysfs.c                         | 7 +++++++
>>   2 files changed, 16 insertions(+)
>>
>> diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
>> index 3ac41774ad3c..a7ce33199457 100644
>> --- a/Documentation/ABI/testing/sysfs-fs-f2fs
>> +++ b/Documentation/ABI/testing/sysfs-fs-f2fs
>> @@ -92,6 +92,15 @@ Contact:	"Jaegeuk Kim" <jaegeuk.kim@samsung.com>
>>   Description:
>>   		 Controls the number of trials to find a victim segment.
>>   
>> +What:		/sys/fs/f2fs/<disk>/migration_granularity
>> +Date:		October 2018
>> +Contact:	"Chao Yu" <yuchao0@huawei.com>
>> +Description:
>> +		 Controls migration granularity of garbage collection on large
>> +		 section, it can let GC move partial segment{s} of one section
>> +		 in one GC cycle, so that dispersing heavy overhead GC to
>> +		 multiple lightweight one.
>> +
>>   What:		/sys/fs/f2fs/<disk>/dir_level
>>   Date:		March 2014
>>   Contact:	"Jaegeuk Kim" <jaegeuk.kim@samsung.com>
>> diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
>> index 240e4881279e..b393fda6d6dc 100644
>> --- a/fs/f2fs/sysfs.c
>> +++ b/fs/f2fs/sysfs.c
>> @@ -246,6 +246,11 @@ static ssize_t __sbi_store(struct f2fs_attr *a,
>>   		return count;
>>   	}
>>   
>> +	if (!strcmp(a->attr.name, "discard_granularity")) {
> 
> Should be migration_granularity ?

Oh, let me fix this in v2.

Thanks,

> 
>> +		if (t == 0 || t > sbi->segs_per_sec)
>> +			return -EINVAL;
>> +	}
>> +
>>   	if (!strcmp(a->attr.name, "trim_sections"))
>>   		return -EINVAL;
>>   
>> @@ -406,6 +411,7 @@ F2FS_RW_ATTR(NM_INFO, f2fs_nm_info, ram_thresh, ram_thresh);
>>   F2FS_RW_ATTR(NM_INFO, f2fs_nm_info, ra_nid_pages, ra_nid_pages);
>>   F2FS_RW_ATTR(NM_INFO, f2fs_nm_info, dirty_nats_ratio, dirty_nats_ratio);
>>   F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, max_victim_search, max_victim_search);
>> +F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, migration_granularity, migration_granularity);
>>   F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, dir_level, dir_level);
>>   F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, cp_interval, interval_time[CP_TIME]);
>>   F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, idle_interval, interval_time[REQ_TIME]);
>> @@ -460,6 +466,7 @@ static struct attribute *f2fs_attrs[] = {
>>   	ATTR_LIST(min_hot_blocks),
>>   	ATTR_LIST(min_ssr_sections),
>>   	ATTR_LIST(max_victim_search),
>> +	ATTR_LIST(migration_granularity),
>>   	ATTR_LIST(dir_level),
>>   	ATTR_LIST(ram_thresh),
>>   	ATTR_LIST(ra_nid_pages),
>