Re: [PATCH 1/5] mm: add PSI accounting around ->read_folio and ->readahead calls

[Jens Axboe <axboe@xxxxxxxxx>]

On 9/10/22 12:50 AM, Christoph Hellwig wrote:
> @@ -2390,8 +2392,13 @@ static int filemap_read_folio(struct file *file, filler_t filler,
>  	 * fails.
>  	 */
>  	folio_clear_error(folio);
> +
>  	/* Start the actual read. The read will unlock the page. */
> +	if (unlikely(workingset))
> +		psi_memstall_enter(&pflags);
>  	error = filler(file, folio);
> +	if (unlikely(workingset))
> +		psi_memstall_leave(&pflags);
>  	if (error)
>  		return error;

I think this would read better as:

  	/* Start the actual read. The read will unlock the page. */
	if (unlikely(workingset)) {
		psi_memstall_enter(&pflags);
		error = filler(file, folio);
		psi_memstall_leave(&pflags);
	} else {
		error = filler(file, folio);
	}
  	if (error)
  		return error;

-- 
Jens Axboe