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From: Jan Kara <jack@suse.cz>
To: Kanchan Joshi <joshi.k@samsung.com>
Cc: linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org,
	linux-ext4@vger.kernel.org, linux-nvme@lists.infradead.org,
	jack@suse.com, david@fromorbit.com, tytso@mit.edu,
	prakash.v@samsung.com
Subject: Re: [PATCH 4/4] fs/ext4,jbd2: add support for passing write-hint with journal.
Date: Thu, 24 Jan 2019 09:50:35 +0100
Message-ID: <20190124085035.GC12184@quack2.suse.cz> (raw)
In-Reply-To: <1547047861-7271-5-git-send-email-joshi.k@samsung.com>

On Wed 09-01-19 21:01:01, Kanchan Joshi wrote:
> For NAND based SSDs, mixing of data with different life-time reduces
> efficiency of internal garbage-collection. During FS operations, series
> of journal updates will follow/precede series of data/meta updates, causing
> intermixing inside SSD. By passing a write-hint with journal, its write
> can be isolated from other data/meta writes, leading to endurance/performance
> benefit on SSD.
> 
> This patch introduces "j_writehint" member in JBD2 journal, using which
> Ext4 specifies write-hint (as SHORT) for journal.
> 
> Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>

Thanks for the patch. It looks mostly good, just one nit below.

> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index d6c142d..3af4049 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -4289,6 +4289,8 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
>  
>  	set_task_ioprio(sbi->s_journal->j_task, journal_ioprio);
>  
> +	sbi->s_journal->j_writehint = KERN_WRITE_LIFE_SHORT;
> +
>  	sbi->s_journal->j_commit_callback = ext4_journal_commit_callback;

So I'd rather have defines like:

#define EXT4_WRITE_HINT_JOURNAL KERN_WRITE_HINT_MIN

like I suggested in another email and then later we could add stuff like

#define EXT4_WRITE_HINT_BITMAP	(KERN_WRITE_HINT_MIN + 1)

etc.

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

  reply index

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CGME20190109153328epcas2p4643cbdc7a2182b47893a2bcaa0778e17@epcas2p4.samsung.com>
2019-01-09 15:30 ` [PATCH v2 0/4] Write-hint for FS journal Kanchan Joshi
     [not found]   ` <CGME20190109153332epcas1p187b419176a8d1d0be4982a275c0b9e86@epcas1p1.samsung.com>
2019-01-09 15:30     ` [PATCH 1/4] block: Increase count of supported write-hints Kanchan Joshi
     [not found]   ` <CGME20190109153336epcas2p29b3275b6c545e483a3f43b92268f08bf@epcas2p2.samsung.com>
2019-01-09 15:30     ` [PATCH 2/4] fs: introduce four macros for in-kernel hints Kanchan Joshi
2019-01-23 18:27       ` [PATCH 2/4] " Javier González
2019-01-24  8:35         ` Jan Kara
2019-01-24  9:23           ` Javier González
     [not found]   ` <CGME20190109153339epcas2p4691a898dde0174a7565d62fcb3be0b6d@epcas2p4.samsung.com>
2019-01-09 15:31     ` [PATCH 3/4] fs: introduce APIs to enable sending write-hint with buffer-head Kanchan Joshi
     [not found]   ` <CGME20190109153342epcas2p3208f62a4dd876f8e1765b48f8aec2432@epcas2p3.samsung.com>
2019-01-09 15:31     ` [PATCH 4/4] fs/ext4,jbd2: add support for passing write-hint with journal Kanchan Joshi
2019-01-24  8:50       ` Jan Kara [this message]
2019-01-23 18:35   ` [PATCH v2 0/4] Write-hint for FS journal Javier González
2019-01-24  8:29   ` Jan Kara
2019-01-25 14:20     ` Kanchan Joshi
2019-01-25 16:23   ` Keith Busch
2019-01-28 12:47     ` Jan Kara
2019-01-28 23:24       ` Keith Busch
2019-01-29 10:07         ` Jan Kara
2019-01-30  0:13           ` Dave Chinner
2019-01-30 13:54             ` Kanchan Joshi
2019-02-05 11:50               ` Jan Kara
2019-02-05 22:53                 ` Dave Chinner

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