2020-11-03 06:42:45

by Daejun Park

Subject: [f2fs-dev] [PATCH] f2fs: change write_hint for hot/warm nodes

From 818a76a9aee5bf225565264274d211edb07bae7d Mon Sep 17 00:00:00 2001
From: Daejun Park <[email protected]>
Date: Tue, 3 Nov 2020 15:30:26 +0900


In the fs-based mode of F2FS, the mapping of hot/warm node to
WRITE_LIFE_NOT_SET should be changed to WRITE_LIFE_SHORT.

As a result of analyzing the write pattern of f2fs using real workload,
hot/warm nodes have high update ratio close to hot data.[*]
However, F2FS passes write hints for hot/warm nodes as WRITE_LIFE_NOT_SET.

Furthermore, WRITE_LIFE_NOT_SET is a default value of write hint when it is
not provided from the file system.
In storage, write_hint is used to distinguish streams (e.g. NVMe).
So, the hot/warm node of F2FS is not distinguished from other write_hints,
which can make the wrong stream seperation.

* Liang, Yu, et al. "An empirical study of F2FS on mobile devices." 2017
IEEE 23rd International Conference on Embedded and Real-Time Computing
Systems and Applications (RTCSA).

Signed-off-by: Daejun Park <[email protected]>
---
fs/f2fs/segment.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 1596502f7375..7b42bb10c6c3 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -3208,7 +3208,7 @@ enum rw_hint f2fs_io_type_to_rw_hint(struct f2fs_sb_info *sbi,
return WRITE_LIFE_EXTREME;
} else if (type == NODE) {
if (temp == WARM || temp == HOT)
- return WRITE_LIFE_NOT_SET;
+ return WRITE_LIFE_SHORT;
else if (temp == COLD)
return WRITE_LIFE_NONE;
} else if (type == META) {
--
2.25.1

2020-11-03 08:32:40

by Chao Yu

Subject: Re: [f2fs-dev] [PATCH] f2fs: change write_hint for hot/warm nodes

On 2020/11/3 14:40, Daejun Park wrote:
>>From 818a76a9aee5bf225565264274d211edb07bae7d Mon Sep 17 00:00:00 2001
> From: Daejun Park <[email protected]>
> Date: Tue, 3 Nov 2020 15:30:26 +0900
>
>
> In the fs-based mode of F2FS, the mapping of hot/warm node to
> WRITE_LIFE_NOT_SET should be changed to WRITE_LIFE_SHORT.
>
> As a result of analyzing the write pattern of f2fs using real workload,
> hot/warm nodes have high update ratio close to hot data.[*]
> However, F2FS passes write hints for hot/warm nodes as WRITE_LIFE_NOT_SET.
>
> Furthermore, WRITE_LIFE_NOT_SET is a default value of write hint when it is
> not provided from the file system.
> In storage, write_hint is used to distinguish streams (e.g. NVMe).
> So, the hot/warm node of F2FS is not distinguished from other write_hints,
> which can make the wrong stream seperation.
>
> * Liang, Yu, et al. "An empirical study of F2FS on mobile devices." 2017
> IEEE 23rd International Conference on Embedded and Real-Time Computing
> Systems and Applications (RTCSA).

Could you please update Documentation/filesystems/f2fs.rst as well?

Thanks,

>
> Signed-off-by: Daejun Park <[email protected]>
> ---
> fs/f2fs/segment.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 1596502f7375..7b42bb10c6c3 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -3208,7 +3208,7 @@ enum rw_hint f2fs_io_type_to_rw_hint(struct f2fs_sb_info *sbi,
> return WRITE_LIFE_EXTREME;
> } else if (type == NODE) {
> if (temp == WARM || temp == HOT)
> - return WRITE_LIFE_NOT_SET;
> + return WRITE_LIFE_SHORT;
> else if (temp == COLD)
> return WRITE_LIFE_NONE;
> } else if (type == META) {
>

2020-11-03 08:35:36

by Daejun Park

Subject: RE: Re: [f2fs-dev] [PATCH] f2fs: change write_hint for hot/warm nodes

>>>From 818a76a9aee5bf225565264274d211edb07bae7d Mon Sep 17 00:00:00 2001
>> From: Daejun Park <[email protected]>
>> Date: Tue, 3 Nov 2020 15:30:26 +0900
>>
>>
>> In the fs-based mode of F2FS, the mapping of hot/warm node to
>> WRITE_LIFE_NOT_SET should be changed to WRITE_LIFE_SHORT.
>>
>> As a result of analyzing the write pattern of f2fs using real workload,
>> hot/warm nodes have high update ratio close to hot data.[*]
>> However, F2FS passes write hints for hot/warm nodes as WRITE_LIFE_NOT_SET.
>>
>> Furthermore, WRITE_LIFE_NOT_SET is a default value of write hint when it is
>> not provided from the file system.
>> In storage, write_hint is used to distinguish streams (e.g. NVMe).
>> So, the hot/warm node of F2FS is not distinguished from other write_hints,
>> which can make the wrong stream seperation.
>>
>> * Liang, Yu, et al. "An empirical study of F2FS on mobile devices." 2017
>> IEEE 23rd International Conference on Embedded and Real-Time Computing
>> Systems and Applications (RTCSA).
>
>Could you please update Documentation/filesystems/f2fs.rst as well?
>
>Thanks,

Sure, I will make it next patch.

Thanks

>>
>> Signed-off-by: Daejun Park <[email protected]>
>> ---
>> fs/f2fs/segment.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
>> index 1596502f7375..7b42bb10c6c3 100644
>> --- a/fs/f2fs/segment.c
>> +++ b/fs/f2fs/segment.c
>> @@ -3208,7 +3208,7 @@ enum rw_hint f2fs_io_type_to_rw_hint(struct f2fs_sb_info *sbi,
>> return WRITE_LIFE_EXTREME;
>> } else if (type == NODE) {
>> if (temp == WARM || temp == HOT)
>> - return WRITE_LIFE_NOT_SET;
>> + return WRITE_LIFE_SHORT;
>> else if (temp == COLD)
>> return WRITE_LIFE_NONE;
>> } else if (type == META) {
>>
>
>