Re: [PATCH 32/39] xfs: convert CIL busy extents to per-cpu

["Darrick J. Wong" <djwong@kernel.org>]

On Wed, May 19, 2021 at 10:13:10PM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
> 
> To get them out from under the CIL lock.
> 
> This is an unordered list, so we can simply punt it to per-cpu lists
> during transaction commits and reaggregate it back into a single
> list during the CIL push work.
> 
> Signed-off-by: Dave Chinner <dchinner@redhat.com>

Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D

> ---
>  fs/xfs/xfs_log_cil.c | 22 +++++++++++++++++++---
>  1 file changed, 19 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/xfs/xfs_log_cil.c b/fs/xfs/xfs_log_cil.c
> index 4ddc302a766b..b12a2f9ba23a 100644
> --- a/fs/xfs/xfs_log_cil.c
> +++ b/fs/xfs/xfs_log_cil.c
> @@ -93,6 +93,11 @@ xlog_cil_pcp_aggregate(
>  
>  		ctx->ticket->t_curr_res += cilpcp->space_reserved;
>  		ctx->ticket->t_unit_res += cilpcp->space_reserved;
> +		if (!list_empty(&cilpcp->busy_extents)) {
> +			list_splice_init(&cilpcp->busy_extents,
> +					&ctx->busy_extents);
> +		}
> +
>  		cilpcp->space_reserved = 0;
>  		cilpcp->space_used = 0;
>  	}
> @@ -523,6 +528,9 @@ xlog_cil_insert_items(
>  		atomic_add(cilpcp->space_used, &ctx->space_used);
>  		cilpcp->space_used = 0;
>  	}
> +	/* attach the transaction to the CIL if it has any busy extents */
> +	if (!list_empty(&tp->t_busy))
> +		list_splice_init(&tp->t_busy, &cilpcp->busy_extents);
>  	put_cpu_ptr(cilpcp);
>  
>  	/*
> @@ -562,9 +570,6 @@ xlog_cil_insert_items(
>  			list_move_tail(&lip->li_cil, &cil->xc_cil);
>  	}
>  
> -	/* attach the transaction to the CIL if it has any busy extents */
> -	if (!list_empty(&tp->t_busy))
> -		list_splice_init(&tp->t_busy, &ctx->busy_extents);
>  	spin_unlock(&cil->xc_cil_lock);
>  
>  	if (tp->t_ticket->t_curr_res < 0)
> @@ -1447,6 +1452,10 @@ xlog_cil_pcp_dead(
>  			ctx->ticket->t_curr_res += cilpcp->space_reserved;
>  			ctx->ticket->t_unit_res += cilpcp->space_reserved;
>  		}
> +		if (!list_empty(&cilpcp->busy_extents)) {
> +			list_splice_init(&cilpcp->busy_extents,
> +					&ctx->busy_extents);
> +		}
>  
>  		cilpcp->space_used = 0;
>  		cilpcp->space_reserved = 0;
> @@ -1502,7 +1511,9 @@ static void __percpu *
>  xlog_cil_pcp_alloc(
>  	struct xfs_cil		*cil)
>  {
> +	struct xlog_cil_pcp	*cilpcp;
>  	void __percpu		*pcp;
> +	int			cpu;
>  
>  	pcp = alloc_percpu(struct xlog_cil_pcp);
>  	if (!pcp)
> @@ -1512,6 +1523,11 @@ xlog_cil_pcp_alloc(
>  		free_percpu(pcp);
>  		return NULL;
>  	}
> +
> +	for_each_possible_cpu(cpu) {
> +		cilpcp = per_cpu_ptr(pcp, cpu);
> +		INIT_LIST_HEAD(&cilpcp->busy_extents);
> +	}
>  	return pcp;
>  }
>  
> -- 
> 2.31.1
>