Re: [RFC PATCH 4/6] hfs: Move long delayed work on system_dfl_long_wq

[Viacheslav Dubeyko <vdubeyko@redhat.com>]

On Fri, 2026-05-08 at 15:45 +0200, Marco Crivellari wrote:
> Currently the code enqueue work items using {queue|mod}_delayed_work(),
> using system_long_wq. This workqueue should be used when long works are
> expected and it is a per-cpu workqueue.
> 
> The function(s) end up calling __queue_delayed_work(), which set a global
> timer that could fire anywhere, enqueuing the work where the timer fired.
> 
> Unbound works could benefit from scheduler task placement, to optimize
> performance and power consumption. Long work shouldn't stick to a single
> CPU.
> 
> Recently, a new unbound workqueue specific for long running work has
> been added:
> 
>     c116737e972e ("workqueue: Add system_dfl_long_wq for long unbound works")
> 
> Since the workqueue work doesn't rely on per-cpu variables, there is no
> obvious reason that justify the use of a per-cpu workqueue. So change
> system_long_wq with system_dfl_long_wq so that the work may benefit from
> scheduler task placement.
> 
> Cc: Viacheslav Dubeyko <slava@dubeyko.com>
> Cc: John Paul Adrian Glaubitz
> Cc: Yangtao Li <frank.li@vivo.com>
> Cc: linux-fsdevel@vger.kernel.org
> Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
> ---
>  fs/hfs/super.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/hfs/super.c b/fs/hfs/super.c
> index a4f2a2bfa6d3..cf4e7a6112e7 100644
> --- a/fs/hfs/super.c
> +++ b/fs/hfs/super.c
> @@ -82,7 +82,7 @@ void hfs_mark_mdb_dirty(struct super_block *sb)
>  	spin_lock(&sbi->work_lock);
>  	if (!sbi->work_queued) {
>  		delay = msecs_to_jiffies(dirty_writeback_interval * 10);
> -		queue_delayed_work(system_long_wq, &sbi->mdb_work, delay);
> +		queue_delayed_work(system_dfl_long_wq, &sbi->mdb_work, delay);
>  		sbi->work_queued = 1;
>  	}
>  	spin_unlock(&sbi->work_lock);

Looks good.

Reviewed-by: Viacheslav Dubeyko <slava@dubeyko.com>

Thanks,
Slava.