On Wed, Jul 16, 2025 at 02:54:06PM +0200, Christoph Hellwig wrote:
> Describe the rationale for the decisions a bit better.
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Looks good,
Reviewed-by: "Darrick J. Wong" <djwong@xxxxxxxxxx>
--D
> ---
> fs/xfs/xfs_zone_alloc.c | 15 +++++++++------
> 1 file changed, 9 insertions(+), 6 deletions(-)
>
> diff --git a/fs/xfs/xfs_zone_alloc.c b/fs/xfs/xfs_zone_alloc.c
> index d9e2b1411434..c1f053f4a82a 100644
> --- a/fs/xfs/xfs_zone_alloc.c
> +++ b/fs/xfs/xfs_zone_alloc.c
> @@ -1114,24 +1114,27 @@ xfs_get_zone_info_cb(
> }
>
> /*
> - * Calculate the max open zone limit based on the of number of
> - * backing zones available
> + * Calculate the max open zone limit based on the of number of backing zones
> + * available.
> */
> static inline uint32_t
> xfs_max_open_zones(
> struct xfs_mount *mp)
> {
> unsigned int max_open, max_open_data_zones;
> +
> /*
> - * We need two zones for every open data zone,
> - * one in reserve as we don't reclaim open zones. One data zone
> - * and its spare is included in XFS_MIN_ZONES.
> + * We need two zones for every open data zone, one in reserve as we
> + * don't reclaim open zones. One data zone and its spare is included
> + * in XFS_MIN_ZONES to support at least one user data writer.
> */
> max_open_data_zones = (mp->m_sb.sb_rgcount - XFS_MIN_ZONES) / 2 + 1;
> max_open = max_open_data_zones + XFS_OPEN_GC_ZONES;
>
> /*
> - * Cap the max open limit to 1/4 of available space
> + * Cap the max open limit to 1/4 of available space. Without this we'd
> + * run out of easy reclaim targets too quickly and storage devices don't
> + * handle huge numbers of concurrent write streams overly well.
> */
> return clamp(max_open, XFS_MIN_OPEN_ZONES, mp->m_sb.sb_rgcount / 4);
> }
> --
> 2.47.2
>
>
