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SubjectRe: [PATCH 1/2] f2fs: set 4KB discard granularity by default
On 08/10, Chao Yu wrote:
> Small granularity (size < 64K) fragmentation will cause f2fs suspending
> all pending discards, result in performance regression, so let's set
> 4KB discard granularity by default.
>
> So that without fstrim, we also have the ability to avoid any performance
> regression caused by non-alignment mapping between fs and flash device.

This is why we added a sysfs entry. Why do we need to change the default
value every time?

>
> Signed-off-by: Chao Yu <yuchao0@huawei.com>
> ---
> fs/f2fs/f2fs.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 58431b9bfd8f..273ffdaf4891 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -248,7 +248,7 @@ struct discard_entry {
> };
>
> /* default discard granularity of inner discard thread, unit: block count */
> -#define DEFAULT_DISCARD_GRANULARITY 16
> +#define DEFAULT_DISCARD_GRANULARITY 1
>
> /* max discard pend list number */
> #define MAX_PLIST_NUM 512
> --
> 2.18.0.rc1

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