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SubjectRe: [PATCH 4/9] readahead: tag mmap page fault call sites
On Tue 29-11-11 21:09:04, Wu Fengguang wrote:
> Introduce a bit field ra->for_mmap for tagging mmap reads.
> The tag will be cleared immediate after submitting the IO.
>
> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Looks OK.
Acked-by: Jan Kara <jack@suse.cz>

Honza
> ---
> include/linux/fs.h | 1 +
> mm/filemap.c | 6 +++++-
> mm/readahead.c | 1 +
> 3 files changed, 7 insertions(+), 1 deletion(-)
>
> --- linux-next.orig/include/linux/fs.h 2011-11-29 10:12:19.000000000 +0800
> +++ linux-next/include/linux/fs.h 2011-11-29 10:13:08.000000000 +0800
> @@ -947,6 +947,7 @@ struct file_ra_state {
> unsigned int ra_pages; /* Maximum readahead window */
> u16 mmap_miss; /* Cache miss stat for mmap accesses */
> u8 pattern; /* one of RA_PATTERN_* */
> + unsigned int for_mmap:1; /* readahead for mmap accesses */
>
> loff_t prev_pos; /* Cache last read() position */
> };
> --- linux-next.orig/mm/filemap.c 2011-11-29 09:48:49.000000000 +0800
> +++ linux-next/mm/filemap.c 2011-11-29 10:13:08.000000000 +0800
> @@ -1592,6 +1592,7 @@ static void do_sync_mmap_readahead(struc
> return;
>
> if (VM_SequentialReadHint(vma)) {
> + ra->for_mmap = 1;
> page_cache_sync_readahead(mapping, ra, file, offset,
> ra->ra_pages);
> return;
> @@ -1611,6 +1612,7 @@ static void do_sync_mmap_readahead(struc
> /*
> * mmap read-around
> */
> + ra->for_mmap = 1;
> ra->pattern = RA_PATTERN_MMAP_AROUND;
> ra_pages = max_sane_readahead(ra->ra_pages);
> ra->start = max_t(long, 0, offset - ra_pages / 2);
> @@ -1636,9 +1638,11 @@ static void do_async_mmap_readahead(stru
> return;
> if (ra->mmap_miss > 0)
> ra->mmap_miss--;
> - if (PageReadahead(page))
> + if (PageReadahead(page)) {
> + ra->for_mmap = 1;
> page_cache_async_readahead(mapping, ra, file,
> page, offset, ra->ra_pages);
> + }
> }
>
> /**
> --- linux-next.orig/mm/readahead.c 2011-11-29 09:48:49.000000000 +0800
> +++ linux-next/mm/readahead.c 2011-11-29 10:13:08.000000000 +0800
> @@ -267,6 +267,7 @@ unsigned long ra_submit(struct file_ra_s
> actual = __do_page_cache_readahead(mapping, filp,
> ra->start, ra->size, ra->async_size);
>
> + ra->for_mmap = 0;
> return actual;
> }
>
>
>
> --
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--
Jan Kara <jack@suse.cz>
SUSE Labs, CR


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