The patch titled
readahead: loop case
has been removed from the -mm tree. Its filename was
readahead-loop-case.patch
This patch was dropped because an updated version will be merged
------------------------------------------------------
Subject: readahead: loop case
From: Wu Fengguang <wfg@xxxxxxxxxxxxxxxx>
Disable look-ahead for loop file.
Loopback files normally contain filesystems, in which case there are already
proper look-aheads in the upper layer, more look-aheads on the loopback file
only ruins the read-ahead hit rate.
Signed-off-by: Wu Fengguang <wfg@xxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/block/loop.c | 6 ++++++
include/linux/fs.h | 1 +
mm/readahead.c | 4 ++++
3 files changed, 11 insertions(+)
diff -puN drivers/block/loop.c~readahead-loop-case drivers/block/loop.c
--- a/drivers/block/loop.c~readahead-loop-case
+++ a/drivers/block/loop.c
@@ -752,6 +752,12 @@ static int loop_set_fd(struct loop_devic
mapping = file->f_mapping;
inode = mapping->host;
+ /* Instruct the readahead code to skip look-ahead on loop file.
+ * The upper layer should already do proper look-ahead,
+ * one more look-ahead here only ruins the cache hit rate.
+ */
+ file->f_ra.flags |= RA_FLAG_LOOP;
+
if (!(file->f_mode & FMODE_WRITE))
lo_flags |= LO_FLAGS_READ_ONLY;
diff -puN include/linux/fs.h~readahead-loop-case include/linux/fs.h
--- a/include/linux/fs.h~readahead-loop-case
+++ a/include/linux/fs.h
@@ -745,6 +745,7 @@ struct file_ra_state {
#define RA_FLAG_MISS (1UL<<31) /* a cache miss occured against this file */
#define RA_FLAG_INCACHE (1UL<<30) /* file is already in cache */
#define RA_FLAG_MMAP (1UL<<29) /* mmap page access */
+#define RA_FLAG_LOOP (1UL<<28) /* loopback file */
struct file {
/*
diff -puN mm/readahead.c~readahead-loop-case mm/readahead.c
--- a/mm/readahead.c~readahead-loop-case
+++ a/mm/readahead.c
@@ -964,6 +964,10 @@ static unsigned long ra_submit(struct fi
ra->lookahead_index = eof;
}
+ /* Disable look-ahead for loopback file. */
+ if (ra->flags & RA_FLAG_LOOP)
+ ra->lookahead_index = ra->readahead_index;
+
/* Take down the current read-ahead aging value. */
ra_save_node_age(ra);
_
Patches currently in -mm which might be from wfg@xxxxxxxxxxxxxxxx are
origin.patch
readahead-loop-case.patch
readahead-nfsd-case.patch
readahead-remove-parameter-ra_max-from-thrashing_recovery_readahead.patch
readahead-remove-parameter-ra_max-from-adjust_rala.patch
readahead-state-based-method-protect-against-tiny-size.patch
readahead-rename-state_based_readahead-to-clock_based_readahead.patch
readahead-account-i-o-block-times-for-stock-readahead.patch
readahead-rescue_pages-updates.patch
readahead-remove-noaction-shrink-events.patch
readahead-remove-size-limit-on-read_ahead_kb.patch
readahead-remove-size-limit-of-max_sectors_kb-on-read_ahead_kb.patch
readahead-partial-sendfile-fix.patch
readahead-turn-on-by-default.patch
-
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
