linux-kernel - Re: [PATCH] f2fs: separate IPU policy for fdatasync from F2FS_IPU

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Message-ID: <8368702c-ae33-b810-a6c3-ac8fa29998df@kernel.org>
Date:   Tue, 8 Nov 2022 22:30:13 +0800
From:   Chao Yu <chao@...nel.org>
To:     qixiaoyu <qxy65535@...il.com>
Cc:     Jaegeuk Kim <jaegeuk@...nel.org>, linux-kernel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net,
        qixiaoyu1 <qixiaoyu1@...omi.com>
Subject: Re: [PATCH] f2fs: separate IPU policy for fdatasync from
 F2FS_IPU_FSYNC

On 2022/11/8 20:32, qixiaoyu wrote:
> On Sun, Nov 06, 2022 at 09:54:59PM +0800, Chao Yu wrote:
>> On 2022/11/2 20:25, qixiaoyu wrote:
>>> Hi Chao,
>>>
>>> fdatasync do in-place-update to avoid additional node writes, but currently
>>> it only do that with F2FS_IPU_FSYNC as:
>>>
>>> f2fs_do_sync_file:
>>> 	if (datasync || get_dirty_pages(inode) <= SM_I(sbi)->min_fsync_blocks)
>>>   		set_inode_flag(inode, FI_NEED_IPU);
>>>
>>> check_inplace_update_policy:
>>> 	/* this is only set during fdatasync */
>>> 	if (policy & (0x1 << F2FS_IPU_FSYNC) &&
>>> 			is_inode_flag_set(inode, FI_NEED_IPU))
>>> 		return true;
>>>
>>> So this patch separate in-place-update of fdatasync from F2FS_IPU_FSYNC to
>>> apply it to all IPU policy.
>>>
>>> BTW, we found small performance improvement with this patch on AndroBench app
>>> using F2FS_IPU_SSR_UTIL on our product:
>>
>> How this patch affects performance when F2FS_IPU_SSR_UTIL is on?
>>
>> Thanks,
>>
> 
> SQLite test in AndroBench app use fdatasync to sync file to the disk.
> When switch to F2FS_IPU_SSR_UTIL ipu_policy, it will use out-of-place-update
> even though SQLite calls fdatasync, which will introduce extra meta data write.

Why not using F2FS_IPU_SSR_UTIL | F2FS_IPU_FSYNC, I guess these two flags
cover different scenarios, F2FS_IPU_SSR_UTIL for ssr case, and F2FS_IPU_FSYNC
for f{data,}sync case.

Thanks,

> 
> Thanks.
> 
>>>
>>>                  F2FS_IPU_FSYNC  F2FS_IPU_SSR_UTIL   F2FS_IPU_SSR_UTIL(with patch)
>>> SQLite Insert(QPS)  6818.08     6327.09(-7.20%)     6757.72
>>> SQLite Update(QPS)  6528.81     6336.57(-2.94%)     6490.77
>>> SQLite Delete(QPS)  9724.68     9378.37(-3.56%)     9622.27
>>>
>>> Thanks
>>>
>>> On Tue, Nov 01, 2022 at 11:14:55PM +0800, Chao Yu wrote:
>>>> On 2022/10/21 10:31, qixiaoyu1 wrote:
>>>>> Currently IPU policy for fdatasync is coupled with F2FS_IPU_FSYNC.
>>>>> Fix to apply it to all IPU policy.
>>>>
>>>> Xiaoyu,
>>>>
>>>> Sorry for the delay.
>>>>
>>>> I didn't get the point, can you please explain more about the
>>>> issue?
>>>>
>>>> Thanks,
>>>>
>>>>>
>>>>> Signed-off-by: qixiaoyu1 <qixiaoyu1@...omi.com>
>>>>> ---
>>>>>   fs/f2fs/data.c | 8 +++-----
>>>>>   fs/f2fs/file.c | 4 +++-
>>>>>   2 files changed, 6 insertions(+), 6 deletions(-)
>>>>>
>>>>> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
>>>>> index a71e818cd67b..fec8e15fe820 100644
>>>>> --- a/fs/f2fs/data.c
>>>>> +++ b/fs/f2fs/data.c
>>>>> @@ -2518,6 +2518,9 @@ static inline bool check_inplace_update_policy(struct inode *inode,
>>>>>   	if (policy & (0x1 << F2FS_IPU_HONOR_OPU_WRITE) &&
>>>>>   			is_inode_flag_set(inode, FI_OPU_WRITE))
>>>>>   		return false;
>>>>> +	/* this is set by fdatasync or F2FS_IPU_FSYNC policy */
>>>>> +	if (is_inode_flag_set(inode, FI_NEED_IPU))
>>>>> +		return true;
>>>>>   	if (policy & (0x1 << F2FS_IPU_FORCE))
>>>>>   		return true;
>>>>>   	if (policy & (0x1 << F2FS_IPU_SSR) && f2fs_need_SSR(sbi))
>>>>> @@ -2538,11 +2541,6 @@ static inline bool check_inplace_update_policy(struct inode *inode,
>>>>>   			!IS_ENCRYPTED(inode))
>>>>>   		return true;
>>>>> -	/* this is only set during fdatasync */
>>>>> -	if (policy & (0x1 << F2FS_IPU_FSYNC) &&
>>>>> -			is_inode_flag_set(inode, FI_NEED_IPU))
>>>>> -		return true;
>>>>> -
>>>>>   	if (unlikely(fio && is_sbi_flag_set(sbi, SBI_CP_DISABLED) &&
>>>>>   			!f2fs_is_checkpointed_data(sbi, fio->old_blkaddr)))
>>>>>   		return true;
>>>>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>>>>> index 82cda1258227..08091550cdf2 100644
>>>>> --- a/fs/f2fs/file.c
>>>>> +++ b/fs/f2fs/file.c
>>>>> @@ -270,8 +270,10 @@ static int f2fs_do_sync_file(struct file *file, loff_t start, loff_t end,
>>>>>   		goto go_write;
>>>>>   	/* if fdatasync is triggered, let's do in-place-update */
>>>>> -	if (datasync || get_dirty_pages(inode) <= SM_I(sbi)->min_fsync_blocks)
>>>>> +	if (datasync || (SM_I(sbi)->ipu_policy & (0x1 << F2FS_IPU_FSYNC) &&
>>>>> +			get_dirty_pages(inode) <= SM_I(sbi)->min_fsync_blocks))
>>>>>   		set_inode_flag(inode, FI_NEED_IPU);
>>>>> +
>>>>>   	ret = file_write_and_wait_range(file, start, end);
>>>>>   	clear_inode_flag(inode, FI_NEED_IPU);