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From: Christoph Hellwig <hch@lst.de>
To: linux-xfs@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org
Subject: [PATCH 04/13] mm: split ->readpages calls to avoid non-contiguous pages lists
Date: Wed, 30 May 2018 11:58:04 +0200	[thread overview]
Message-ID: <20180530095813.31245-5-hch@lst.de> (raw)
In-Reply-To: <20180530095813.31245-1-hch@lst.de>

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: Darrick J. Wong <darrick.wong@oracle.com>
---
 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

  parent reply	other threads:[~2018-05-30  9:58 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-30  9:58 iomap based buffered reads & iomap cleanups v4 Christoph Hellwig
2018-05-30  9:58 ` [PATCH 01/13] block: add a lower-level bio_add_page interface Christoph Hellwig
2018-05-30 10:12   ` Ming Lei
2018-05-30  9:58 ` [PATCH 02/13] mm: give the 'ret' variable a better name __do_page_cache_readahead Christoph Hellwig
2018-05-30 23:01   ` Dave Chinner
2018-05-30  9:58 ` [PATCH 03/13] mm: return an unsigned int from __do_page_cache_readahead Christoph Hellwig
2018-05-30 23:02   ` Dave Chinner
2018-05-30  9:58 ` Christoph Hellwig [this message]
2018-05-30 23:02   ` [PATCH 04/13] mm: split ->readpages calls to avoid non-contiguous pages lists Dave Chinner
2018-05-30  9:58 ` [PATCH 05/13] iomap: inline data should be an iomap type, not a flag Christoph Hellwig
2018-05-30 23:05   ` Dave Chinner
2018-05-30  9:58 ` [PATCH 06/13] iomap: fix the comment describing IOMAP_NOWAIT Christoph Hellwig
2018-05-30 23:05   ` Dave Chinner
2018-05-30  9:58 ` [PATCH 07/13] iomap: move IOMAP_F_BOUNDARY to gfs2 Christoph Hellwig
2018-05-30 23:08   ` Dave Chinner
2018-05-30  9:58 ` [PATCH 08/13] iomap: use __bio_add_page in iomap_dio_zero Christoph Hellwig
2018-05-30 23:09   ` Dave Chinner
2018-05-30  9:58 ` [PATCH 09/13] iomap: add a iomap_sector helper Christoph Hellwig
2018-05-30 23:10   ` Dave Chinner
2018-05-30  9:58 ` [PATCH 10/13] iomap: add an iomap-based bmap implementation Christoph Hellwig
2018-05-30 23:11   ` Dave Chinner
2018-05-31  6:07     ` Christoph Hellwig
2018-05-30  9:58 ` [PATCH 11/13] iomap: add an iomap-based readpage and readpages implementation Christoph Hellwig
2018-05-30 16:22   ` Darrick J. Wong
2018-05-30 23:45   ` Dave Chinner
2018-05-31  6:13     ` Christoph Hellwig
2018-05-31 11:59       ` Dave Chinner
2018-05-30  9:58 ` [PATCH 12/13] xfs: use iomap_bmap Christoph Hellwig
2018-05-30 23:46   ` Dave Chinner
2018-05-30  9:58 ` [PATCH 13/13] xfs: use iomap for blocksize == PAGE_SIZE readpage and readpages Christoph Hellwig
2018-05-30 23:47   ` Dave Chinner
2018-05-31 18:06 iomap based buffered reads & iomap cleanups v5 Christoph Hellwig
2018-05-31 18:06 ` [PATCH 04/13] mm: split ->readpages calls to avoid non-contiguous pages lists Christoph Hellwig

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