diff options
| author | Christoph Hellwig <hch@lst.de> | 2018-06-01 09:03:06 -0700 |
|---|---|---|
| committer | Darrick J. Wong <darrick.wong@oracle.com> | 2018-06-01 18:37:32 -0700 |
| commit | b3751e6ab45a3b92da1e4acd42ada7b6a4122f2b (patch) | |
| tree | 89da8a8cbe40bb7258ec11861e3b4f18db026537 /mm/readahead.c | |
| parent | c534aa3fdd149fab18b094375f334b4bb3635cbf (diff) | |
mm: split ->readpages calls to avoid non-contiguous pages lists
That way file systems don't have to go spotting for non-contiguous pages
and work around them. It also kicks off I/O earlier, allowing it to
finish earlier and reduce latency.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Diffstat (limited to 'mm/readahead.c')
| -rw-r--r-- | mm/readahead.c | 16 |
1 files changed, 13 insertions, 3 deletions
diff --git a/mm/readahead.c b/mm/readahead.c index fa4d4b767130..e273f0de3376 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -140,8 +140,8 @@ out: } /* - * __do_page_cache_readahead() actually reads a chunk of disk. It allocates all - * the pages first, then submits them all for I/O. This avoids the very bad + * __do_page_cache_readahead() actually reads a chunk of disk. It allocates + * the pages first, then submits them for I/O. This avoids the very bad * behaviour which would occur if page allocations are causing VM writeback. * We really don't want to intermingle reads and writes like that. * @@ -177,8 +177,18 @@ unsigned int __do_page_cache_readahead(struct address_space *mapping, rcu_read_lock(); page = radix_tree_lookup(&mapping->i_pages, page_offset); rcu_read_unlock(); - if (page && !radix_tree_exceptional_entry(page)) + if (page && !radix_tree_exceptional_entry(page)) { + /* + * Page already present? Kick off the current batch of + * contiguous pages before continuing with the next + * batch. + */ + if (nr_pages) + read_pages(mapping, filp, &page_pool, nr_pages, + gfp_mask); + nr_pages = 0; continue; + } page = __page_cache_alloc(gfp_mask); if (!page) |