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From: Chao Yu <>
To: Damien Le Moal <>,
	Jaegeuk Kim <>,
Cc: <>,
	Matias Bjorling <>,
	Masato Suzuki <>
Subject: Re: [PATCH 2/3] f2fs: Reduce zoned block device memory usage
Date: Tue, 19 Mar 2019 19:01:21 +0800	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On 2019/3/16 8:13, Damien Le Moal wrote:
> For zoned block devices, an array of zone types for each device is
> allocated and initialized in order to determine if a section is stored
> on a sequential zone (zone reset needed) or a conventional zone (no
> zone reset needed and regular discard applies). Considering this usage,
> the zone types stored in memory can be replaced with a bitmap to
> indicate an equivalent information, that is, if a zone is sequential or
> not. This reduces the memory usage for each zoned device by roughly 8:
> on a 14TB disk with zones of 256 MB, the zone type array consumes
> 13x4KB pages while the bitmap uses only 2x4KB pages.
> This patch changes the f2fs_dev_info structure blkz_type field to the
> bitmap blkz_seq. Access to this bitmap is done using the helper
> function f2fs_blkz_is_seq(), which is a rewrite of the function
> get_blkz_type().
> Signed-off-by: Damien Le Moal <>

Reviewed-by: Chao Yu <>


  reply	other threads:[~2019-03-19 11:01 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-16  0:13 [PATCH V2 0/3] f2fs: bug fix and improvement Damien Le Moal
2019-03-16  0:13 ` [PATCH 1/3] f2fs: Fix use of number of devices Damien Le Moal
2019-03-16  0:13 ` [PATCH 2/3] f2fs: Reduce zoned block device memory usage Damien Le Moal
2019-03-19 11:01   ` Chao Yu [this message]
2019-03-16  0:13 ` [PATCH 3/3] f2fs: improve discard handling with multi-device volumes Damien Le Moal
2019-03-19 11:02   ` Chao Yu

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