This patch adds the ability to drop mapped pages with
/proc/sys/vm/drop_caches. This is useful to get repeatable
measurements of startup time for applications.
Without it, pages that are mapped in already-running applications will
not get dropped, so the time measured will not be a true cold-cache
time.
Rik pointed out that "be_atomic" is a bit pointless since there is a
race on SMP anyway where pages can be added. However, it is there in
the existing code, so I added it for the new code as well. Does anyone
know why it's there?
Soren
Signed-off-by: Soren Sandmann <[email protected]>
---
fs/drop_caches.c | 13 ++++++++-----
include/linux/fs.h | 3 +++
include/linux/mm.h | 2 +-
mm/truncate.c | 36 ++++++++++++++++++++++--------------
4 files changed, 34 insertions(+), 20 deletions(-)
diff --git a/fs/drop_caches.c b/fs/drop_caches.c
index 59375ef..9f3741d 100644
--- a/fs/drop_caches.c
+++ b/fs/drop_caches.c
@@ -12,7 +12,7 @@
/* A global variable is a bit ugly, but it keeps the code simple */
int sysctl_drop_caches;
-static void drop_pagecache_sb(struct super_block *sb)
+static void drop_pagecache_sb(struct super_block *sb, int unmap)
{
struct inode *inode;
@@ -20,12 +20,15 @@ static void drop_pagecache_sb(struct super_block *sb)
list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
if (inode->i_state & (I_FREEING|I_WILL_FREE))
continue;
- __invalidate_mapping_pages(inode->i_mapping, 0, -1, true);
+ if (unmap)
+ __invalidate_inode_pages2_range(inode->i_mapping, 0, -1, true);
+ else
+ __invalidate_mapping_pages(inode->i_mapping, 0, -1, true);
}
spin_unlock(&inode_lock);
}
-void drop_pagecache(void)
+void drop_pagecache(int unmap)
{
struct super_block *sb;
@@ -36,7 +39,7 @@ restart:
spin_unlock(&sb_lock);
down_read(&sb->s_umount);
if (sb->s_root)
- drop_pagecache_sb(sb);
+ drop_pagecache_sb(sb, unmap);
up_read(&sb->s_umount);
spin_lock(&sb_lock);
if (__put_super_and_need_restart(sb))
@@ -60,7 +63,7 @@ int drop_caches_sysctl_handler(ctl_table *table, int write,
proc_dointvec_minmax(table, write, file, buffer, length, ppos);
if (write) {
if (sysctl_drop_caches & 1)
- drop_pagecache();
+ drop_pagecache(sysctl_drop_caches & 4);
if (sysctl_drop_caches & 2)
drop_slab();
}
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 16421f6..c112aa3 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1536,6 +1536,9 @@ static inline void invalidate_remote_inode(struct inode *inode)
invalidate_mapping_pages(inode->i_mapping, 0, -1);
}
extern int invalidate_inode_pages2(struct address_space *mapping);
+extern int __invalidate_inode_pages2_range(struct address_space *mapping,
+ pgoff_t start, pgoff_t end,
+ int be_atomic);
extern int invalidate_inode_pages2_range(struct address_space *mapping,
pgoff_t start, pgoff_t end);
extern int write_inode_now(struct inode *, int);
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 1692dd6..6719c41 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1207,7 +1207,7 @@ int drop_caches_sysctl_handler(struct ctl_table *, int, struct file *,
void __user *, size_t *, loff_t *);
unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask,
unsigned long lru_pages);
-void drop_pagecache(void);
+void drop_pagecache(int unmap);
void drop_slab(void);
#ifndef CONFIG_MMU
diff --git a/mm/truncate.c b/mm/truncate.c
index 5cdfbc1..568ac77 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -371,19 +371,9 @@ static int do_launder_page(struct address_space *mapping, struct page *page)
return mapping->a_ops->launder_page(page);
}
-/**
- * invalidate_inode_pages2_range - remove range of pages from an address_space
- * @mapping: the address_space
- * @start: the page offset 'from' which to invalidate
- * @end: the page offset 'to' which to invalidate (inclusive)
- *
- * Any pages which are found to be mapped into pagetables are unmapped prior to
- * invalidation.
- *
- * Returns -EIO if any pages could not be invalidated.
- */
-int invalidate_inode_pages2_range(struct address_space *mapping,
- pgoff_t start, pgoff_t end)
+int __invalidate_inode_pages2_range(struct address_space *mapping,
+ pgoff_t start, pgoff_t end,
+ int be_atomic)
{
struct pagevec pvec;
pgoff_t next;
@@ -442,10 +432,28 @@ int invalidate_inode_pages2_range(struct address_space *mapping,
unlock_page(page);
}
pagevec_release(&pvec);
- cond_resched();
+ if (likely(!be_atomic))
+ cond_resched();
}
return ret;
}
+
+/**
+ * invalidate_inode_pages2_range - remove range of pages from an address_space
+ * @mapping: the address_space
+ * @start: the page offset 'from' which to invalidate
+ * @end: the page offset 'to' which to invalidate (inclusive)
+ *
+ * Any pages which are found to be mapped into pagetables are unmapped prior to
+ * invalidation.
+ *
+ * Returns -EIO if any pages could not be invalidated.
+ */
+int invalidate_inode_pages2_range(struct address_space *mapping,
+ pgoff_t start, pgoff_t end)
+{
+ return __invalidate_inode_pages2_range(mapping, start, end, false);
+}
EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range);
/**
--
1.5.2.4
-
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