Re: [PATCH] fs: Optimize unixbench's file copy test

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

On Fri, Jun 30, 2023 at 05:28:23PM +0800, zenghongling wrote:
> The iomap_set_range_uptodate function checks if the file is a private
> mapping,and if it is, it needs to do something about it.UnixBench's
> file copy tests are mostly share mapping, such a check would reduce
> file copy scores, so we added the unlikely macro for optimization.
> and the score of file copy can be improved after branch optimization.
> As follows:
> 
> ./Run -c 8 -i 3 fstime fsbuffer fsdisk
> 
> Before the optimization
> System Benchmarks Partial Index              BASELINE       RESULT    INDEX
> File Copy 1024 bufsize 2000 maxblocks          3960.0     689276.0   1740.6
> File Copy 256 bufsize 500 maxblocks            1655.0     204133.0   1233.4
> File Copy 4096 bufsize 8000 maxblocks          5800.0    1526945.0   2632.7
>                                                                    ========
> System Benchmarks Index Score (Partial Only)                         1781.3
> 
> After the optimization
> System Benchmarks Partial Index              BASELINE       RESULT    INDEX
> File Copy 1024 bufsize 2000 maxblocks          3960.0     741524.0   1872.5
> File Copy 256 bufsize 500 maxblocks            1655.0     208334.0   1258.8
> File Copy 4096 bufsize 8000 maxblocks          5800.0    1641660.0   2830.4
>                                                                    ========
> System Benchmarks Index Score (Partial Only)                         1882.6

Kernel version?  And how does this intersect with the ongoing work to
use large folios throughout iomap?

--D

> Signed-off-by: zenghongling <zenghongling@kylinos.cn>
> ---
>  fs/iomap/buffered-io.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
> index 53cd7b2..35a50c2 100644
> --- a/fs/iomap/buffered-io.c
> +++ b/fs/iomap/buffered-io.c
> @@ -148,7 +148,7 @@ iomap_set_range_uptodate(struct page *page, unsigned off, unsigned len)
>  	if (PageError(page))
>  		return;
>  
> -	if (page_has_private(page))
> +	if (unlikely(page_has_private(page)))
>  		iomap_iop_set_range_uptodate(page, off, len);
>  	else
>  		SetPageUptodate(page);
> -- 
> 2.1.0
>