The patch titled
readahead: min/max sizes
has been added to the -mm tree. Its filename is
readahead-min-max-sizes.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: readahead: min/max sizes
From: Wu Fengguang <wfg@xxxxxxxxxxxxxxxx>
- Enlarge VM_MAX_READAHEAD to 1024 if new read-ahead code is compiled in.
This value is no longer tightly coupled with the thrashing problem,
therefore constrained by it. The adaptive read-ahead logic merely takes
it as an upper bound, and will not stick to it under memory pressure.
- Slightly enlarge minimal/initial read-ahead size on big memory systems.
Memory bounty systems are less likely to suffer from thrashing on small
read-ahead sizes. A bigger initial value helps the ra_size scaling up
progress.
Signed-off-by: Wu Fengguang <wfg@xxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
include/linux/mm.h | 4 ++++
mm/readahead.c | 24 ++++++++++++++++++++++++
2 files changed, 28 insertions(+)
diff -puN include/linux/mm.h~readahead-min-max-sizes include/linux/mm.h
--- a/include/linux/mm.h~readahead-min-max-sizes
+++ a/include/linux/mm.h
@@ -1046,7 +1046,11 @@ extern int filemap_populate(struct vm_ar
int write_one_page(struct page *page, int wait);
/* readahead.c */
+#ifdef CONFIG_ADAPTIVE_READAHEAD
+#define VM_MAX_READAHEAD 1024 /* kbytes */
+#else
#define VM_MAX_READAHEAD 128 /* kbytes */
+#endif
#define VM_MIN_READAHEAD 16 /* kbytes (includes current page) */
#define VM_MAX_CACHE_HIT 256 /* max pages in a row in cache before
* turning readahead off */
diff -puN mm/readahead.c~readahead-min-max-sizes mm/readahead.c
--- a/mm/readahead.c~readahead-min-max-sizes
+++ a/mm/readahead.c
@@ -779,6 +779,30 @@ out:
return nr_pages;
}
+/*
+ * ra_min is mainly determined by the size of cache memory. Reasonable?
+ *
+ * Table of concrete numbers for 4KB page size:
+ * inactive + free (MB): 4 8 16 32 64 128 256 512 1024
+ * ra_min (KB): 16 16 16 16 20 24 32 48 64
+ */
+static inline void get_readahead_bounds(struct file_ra_state *ra,
+ unsigned long *ra_min,
+ unsigned long *ra_max)
+{
+ unsigned long active;
+ unsigned long inactive;
+ unsigned long free;
+
+ __get_zone_counts(&active, &inactive, &free, NODE_DATA(numa_node_id()));
+
+ free += inactive;
+ *ra_max = min(min(ra->ra_pages, 0xFFFFUL), free / 2);
+ *ra_min = min(min(MIN_RA_PAGES + (free >> 14),
+ DIV_ROUND_UP(64*1024, PAGE_CACHE_SIZE)),
+ *ra_max / 8);
+}
+
#endif /* CONFIG_ADAPTIVE_READAHEAD */
/*
_
Patches currently in -mm which might be from wfg@xxxxxxxxxxxxxxxx are
readahead-kconfig-options.patch
radixtree-introduce-scan-hole-data-functions.patch
mm-introduce-probe_page.patch
mm-introduce-pg_readahead.patch
readahead-add-look-ahead-support-to-__do_page_cache_readahead.patch
readahead-insert-cond_resched-calls.patch
readahead-minmax_ra_pages.patch
readahead-events-accounting.patch
readahead-rescue_pages.patch
readahead-sysctl-parameters.patch
readahead-min-max-sizes.patch
readahead-state-based-method-aging-accounting.patch
readahead-state-based-method-routines.patch
readahead-state-based-method.patch
readahead-context-based-method.patch
readahead-initial-method-guiding-sizes.patch
readahead-initial-method-thrashing-guard-size.patch
readahead-initial-method-user-recommended-size.patch
readahead-initial-method.patch
readahead-backward-prefetching-method.patch
readahead-thrashing-recovery-method.patch
readahead-call-scheme.patch
readahead-laptop-mode.patch
readahead-loop-case.patch
readahead-nfsd-case.patch
readahead-turn-on-by-default.patch
readahead-remove-size-limit-on-read_ahead_kb.patch
readahead-remove-size-limit-of-max_sectors_kb-on-read_ahead_kb.patch
-
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