Re: [PATCH 2/3] f2fs: Reduce zoned block device memory usage

[Chao Yu <yuchao0@huawei.com>]

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 <damien.lemoal@wdc.com>

Reviewed-by: Chao Yu <yuchao0@huawei.com>

Thanks,