* [RFC PATCH] mm : using bdi->ra_pages instead of ra->ra_pages within readahead
@ 2020-08-13 8:11 Zhaoyang Huang
2020-08-13 11:19 ` Matthew Wilcox
0 siblings, 1 reply; 2+ messages in thread
From: Zhaoyang Huang @ 2020-08-13 8:11 UTC (permalink / raw)
To: Roman Gushchin, Andrew Morton, Zhaoyang Huang, linux-mm, linux-kernel
file->f_ra->ra_pages will remain the initialized value since it opend, which may
be NOT equal to bdi->ra_pages as the latter one is updated somehow(etc,
echo xxx > /sys/block/dm/queue/read_ahead_kb).So having readahead use
bdi->ra_pages.
Signed-off-by: Zhaoyang Huang <zhaoyang.huang@unisoc.com>
---
mm/filemap.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/mm/filemap.c b/mm/filemap.c
index d78f577..259dcfd 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2499,8 +2499,8 @@ static struct file *do_sync_mmap_readahead(struct vm_fault *vmf)
*/
fpin = maybe_unlock_mmap_for_io(vmf, fpin);
ra->start = max_t(long, 0, offset - ra->ra_pages / 2);
- ra->size = ra->ra_pages;
- ra->async_size = ra->ra_pages / 4;
+ ra->size = inode_to_bdi(mapping->host)->ra_pages;
+ ra->async_size = ra->size / 4;
ra_submit(ra, mapping, file);
return fpin;
}
--
1.9.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [RFC PATCH] mm : using bdi->ra_pages instead of ra->ra_pages within readahead
2020-08-13 8:11 [RFC PATCH] mm : using bdi->ra_pages instead of ra->ra_pages within readahead Zhaoyang Huang
@ 2020-08-13 11:19 ` Matthew Wilcox
0 siblings, 0 replies; 2+ messages in thread
From: Matthew Wilcox @ 2020-08-13 11:19 UTC (permalink / raw)
To: Zhaoyang Huang
Cc: Roman Gushchin, Andrew Morton, Zhaoyang Huang, linux-mm, linux-kernel
On Thu, Aug 13, 2020 at 04:11:22PM +0800, Zhaoyang Huang wrote:
> file->f_ra->ra_pages will remain the initialized value since it opend, which may
> be NOT equal to bdi->ra_pages as the latter one is updated somehow(etc,
> echo xxx > /sys/block/dm/queue/read_ahead_kb).So having readahead use
> bdi->ra_pages.
But now it ignores the work done by shrink_readahead_size_eio()
and fadvise(POSIX_FADV_SEQUENTIAL). And you missed the use of ra_size
on the previous line, miscalculating ra->start.
> Signed-off-by: Zhaoyang Huang <zhaoyang.huang@unisoc.com>
> ---
> mm/filemap.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/mm/filemap.c b/mm/filemap.c
> index d78f577..259dcfd 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -2499,8 +2499,8 @@ static struct file *do_sync_mmap_readahead(struct vm_fault *vmf)
> */
> fpin = maybe_unlock_mmap_for_io(vmf, fpin);
> ra->start = max_t(long, 0, offset - ra->ra_pages / 2);
> - ra->size = ra->ra_pages;
> - ra->async_size = ra->ra_pages / 4;
> + ra->size = inode_to_bdi(mapping->host)->ra_pages;
> + ra->async_size = ra->size / 4;
> ra_submit(ra, mapping, file);
> return fpin;
> }
> --
> 1.9.1
>
>
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2020-08-13 11:19 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-08-13 8:11 [RFC PATCH] mm : using bdi->ra_pages instead of ra->ra_pages within readahead Zhaoyang Huang
2020-08-13 11:19 ` Matthew Wilcox
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).