| Message ID | 20180523144357.18985-9-hch@lst.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, May 23, 2018 at 04:43:31PM +0200, Christoph Hellwig wrote: > 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> Looks ok, if anyone has a strong opinion they better yell soon... Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> --D > --- > mm/readahead.c | 16 +++++++++++++--- > 1 file 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 @@ static int read_pages(struct address_space *mapping, struct file *filp, > } > > /* > - * __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) > -- > 2.17.0 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html
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 @@ static int read_pages(struct address_space *mapping, struct file *filp, } /* - * __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)
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> --- mm/readahead.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-)