linux-kernel - Re: [f2fs-dev] [PATCH 1/5] f2fs: change default compression algorithm

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Date:   Wed, 11 Mar 2020 08:41:35 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     Eric Biggers <ebiggers@...nel.org>
CC:     <jaegeuk@...nel.org>, <linux-kernel@...r.kernel.org>,
        <linux-f2fs-devel@...ts.sourceforge.net>
Subject: Re: [f2fs-dev] [PATCH 1/5] f2fs: change default compression algorithm

On 2020/3/11 0:15, Eric Biggers wrote:
> On Tue, Mar 10, 2020 at 08:50:05PM +0800, Chao Yu wrote:
>> Use LZ4 as default compression algorithm, as compared to LZO, it shows
>> almost the same compression ratio and much better decompression speed.
>>
>> Signed-off-by: Chao Yu <yuchao0@...wei.com>
>> ---
>>  fs/f2fs/super.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
>> index db3a63f7c769..ebffe7aa08ee 100644
>> --- a/fs/f2fs/super.c
>> +++ b/fs/f2fs/super.c
>> @@ -1577,7 +1577,7 @@ static void default_options(struct f2fs_sb_info *sbi)
>>  	F2FS_OPTION(sbi).test_dummy_encryption = false;
>>  	F2FS_OPTION(sbi).s_resuid = make_kuid(&init_user_ns, F2FS_DEF_RESUID);
>>  	F2FS_OPTION(sbi).s_resgid = make_kgid(&init_user_ns, F2FS_DEF_RESGID);
>> -	F2FS_OPTION(sbi).compress_algorithm = COMPRESS_LZO;
>> +	F2FS_OPTION(sbi).compress_algorithm = COMPRESS_LZ4;
>>  	F2FS_OPTION(sbi).compress_log_size = MIN_COMPRESS_LOG_SIZE;
>>  	F2FS_OPTION(sbi).compress_ext_cnt = 0;
>>  	F2FS_OPTION(sbi).bggc_mode = BGGC_MODE_ON;
> 
> This makes sense, but it's unclear to me why comparing the different compression
> algorithms is happening just now, after support for both LZO and LZ4 was already
> merged into mainline and now has to be supported forever.  During review months
> ago, multiple people suggested that LZ4 is better than LZO, so there's not much
> reason to support LZO at all.

Agreed,

Jaegeuk, thoughts?

Let me remove lzo if you have no objection on this.

Thanks,

> 
> - Eric
> .
>