From: Miklos Szeredi <mszeredi@xxxxxxx>
Move BDI statistics to debugfs:
/sys/kernel/debug/bdi/<bdi>/stats
Use postcore_initcall() to initialize the sysfs class and debugfs,
because debugfs is initialized in core_initcall().
Update descriptions in ABI documentation.
Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxx>
---
Index: linux/include/linux/backing-dev.h
===================================================================
--- linux.orig/include/linux/backing-dev.h 2008-02-02 23:08:41.000000000 +0100
+++ linux/include/linux/backing-dev.h 2008-02-02 23:08:41.000000000 +0100
@@ -16,6 +16,7 @@
#include <asm/atomic.h>
struct page;
+struct dentry;
/*
* Bits in backing_dev_info.state
@@ -55,6 +56,11 @@ struct backing_dev_info {
unsigned int max_ratio, max_prop_frac;
struct device *dev;
+
+#ifdef CONFIG_DEBUG_FS
+ struct dentry *debug_dir;
+ struct dentry *debug_stats;
+#endif
};
int bdi_init(struct backing_dev_info *bdi);
Index: linux/mm/backing-dev.c
===================================================================
--- linux.orig/mm/backing-dev.c 2008-02-02 23:08:41.000000000 +0100
+++ linux/mm/backing-dev.c 2008-02-02 23:12:47.000000000 +0100
@@ -10,6 +10,80 @@
static struct class *bdi_class;
+#ifdef CONFIG_DEBUG_FS
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
+
+static struct dentry *bdi_debug_root;
+
+static void bdi_debug_init(void)
+{
+ bdi_debug_root = debugfs_create_dir("bdi", NULL);
+}
+
+static int bdi_debug_stats_show(struct seq_file *m, void *v)
+{
+ struct backing_dev_info *bdi = m->private;
+ long background_thresh;
+ long dirty_thresh;
+ long bdi_thresh;
+
+ get_dirty_limits(&background_thresh, &dirty_thresh, &bdi_thresh, bdi);
+
+#define K(x) ((x) << (PAGE_SHIFT - 10))
+ seq_printf(m,
+ "BdiWriteback: %8lu kB\n"
+ "BdiReclaimable: %8lu kB\n"
+ "BdiDirtyThresh: %8lu kB\n"
+ "DirtyThresh: %8lu kB\n"
+ "BackgroundThresh: %8lu kB\n",
+ (unsigned long) K(bdi_stat(bdi, BDI_WRITEBACK)),
+ (unsigned long) K(bdi_stat(bdi, BDI_RECLAIMABLE)),
+ K(bdi_thresh),
+ K(dirty_thresh),
+ K(background_thresh));
+#undef K
+
+ return 0;
+}
+
+static int bdi_debug_stats_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, bdi_debug_stats_show, inode->i_private);
+}
+
+static const struct file_operations bdi_debug_stats_fops = {
+ .open = bdi_debug_stats_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
+static void bdi_debug_register(struct backing_dev_info *bdi, const char *name)
+{
+ bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root);
+ bdi->debug_stats = debugfs_create_file("stats", 0444, bdi->debug_dir,
+ bdi, &bdi_debug_stats_fops);
+}
+
+static void bdi_debug_unregister(struct backing_dev_info *bdi)
+{
+ debugfs_remove(bdi->debug_stats);
+ debugfs_remove(bdi->debug_dir);
+}
+#else
+static inline void bdi_debug_init(void)
+{
+}
+static inline void bdi_debug_register(struct backing_dev_info *bdi,
+ const char *name)
+{
+}
+static inline void bdi_debug_unregister(struct backing_dev_info *bdi)
+{
+}
+#endif
+
static ssize_t read_ahead_kb_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
@@ -40,21 +114,6 @@ static ssize_t name##_show(struct device
BDI_SHOW(read_ahead_kb, K(bdi->ra_pages))
-BDI_SHOW(reclaimable_kb, K(bdi_stat(bdi, BDI_RECLAIMABLE)))
-BDI_SHOW(writeback_kb, K(bdi_stat(bdi, BDI_WRITEBACK)))
-
-static inline unsigned long get_dirty(struct backing_dev_info *bdi, int i)
-{
- unsigned long thresh[3];
-
- get_dirty_limits(&thresh[0], &thresh[1], &thresh[2], bdi);
-
- return thresh[i];
-}
-
-BDI_SHOW(dirty_kb, K(get_dirty(bdi, 1)))
-BDI_SHOW(bdi_dirty_kb, K(get_dirty(bdi, 2)))
-
static ssize_t min_ratio_store(struct device *dev,
struct device_attribute *attr, const char *buf, size_t count)
{
@@ -95,10 +154,6 @@ BDI_SHOW(max_ratio, bdi->max_ratio)
static struct device_attribute bdi_dev_attrs[] = {
__ATTR_RW(read_ahead_kb),
- __ATTR_RO(reclaimable_kb),
- __ATTR_RO(writeback_kb),
- __ATTR_RO(dirty_kb),
- __ATTR_RO(bdi_dirty_kb),
__ATTR_RW(min_ratio),
__ATTR_RW(max_ratio),
__ATTR_NULL,
@@ -108,10 +163,11 @@ static __init int bdi_class_init(void)
{
bdi_class = class_create(THIS_MODULE, "bdi");
bdi_class->dev_attrs = bdi_dev_attrs;
+ bdi_debug_init();
return 0;
}
-core_initcall(bdi_class_init);
+postcore_initcall(bdi_class_init);
int bdi_register(struct backing_dev_info *bdi, struct device *parent,
const char *fmt, ...)
@@ -136,6 +192,7 @@ int bdi_register(struct backing_dev_info
bdi->dev = dev;
dev_set_drvdata(bdi->dev, bdi);
+ bdi_debug_register(bdi, name);
exit:
kfree(name);
@@ -152,6 +209,7 @@ EXPORT_SYMBOL(bdi_register_dev);
void bdi_unregister(struct backing_dev_info *bdi)
{
if (bdi->dev) {
+ bdi_debug_unregister(bdi);
device_unregister(bdi->dev);
bdi->dev = NULL;
}
Index: linux/Documentation/ABI/testing/sysfs-class-bdi
===================================================================
--- linux.orig/Documentation/ABI/testing/sysfs-class-bdi 2008-02-02 23:08:41.000000000 +0100
+++ linux/Documentation/ABI/testing/sysfs-class-bdi 2008-02-02 23:17:27.000000000 +0100
@@ -3,8 +3,8 @@ Date: January 2008
Contact: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Description:
-Provide a place in sysfs for the backing_dev_info object.
-This allows us to see and set the various BDI specific variables.
+Provide a place in sysfs for the backing_dev_info object. This allows
+setting and retrieving various BDI specific variables.
The <bdi> identifier can be either of the following:
@@ -26,34 +26,21 @@ read_ahead_kb (read-write)
Size of the read-ahead window in kilobytes
-reclaimable_kb (read-only)
-
- Reclaimable (dirty or unstable) memory destined for writeback
- to this device
-
-writeback_kb (read-only)
-
- Memory currently under writeback to this device
-
-dirty_kb (read-only)
-
- Global threshold for reclaimable + writeback memory
-
-bdi_dirty_kb (read-only)
-
- Current threshold on this BDI for reclaimable + writeback
- memory
-
min_ratio (read-write)
- Minimal percentage of global dirty threshold allocated to this
- bdi. If the value written to this file would make the the sum
- of all min_ratio values exceed 100, then EINVAL is returned.
- If min_ratio would become larger than the current max_ratio,
- then also EINVAL is returned. The default is zero
+ Under normal circumstances each device is given a part of the
+ total write-back cache that relates to its current average
+ writeout speed in relation to the other devices.
+
+ The 'min_ratio' parameter allows assigning a minimum
+ percentage of the write-back cache to a particular device.
+ For example, this is useful for providing a minimum QoS.
max_ratio (read-write)
- Maximal percentage of global dirty threshold allocated to this
- bdi. If max_ratio would become smaller than the current
- min_ratio, then EINVAL is returned. The default is 100
+ Allows limiting a particular device to use not more than the
+ given percentage of the write-back cache. This is useful in
+ situations where we want to avoid one device taking all or
+ most of the write-back cache. For example in case of an NFS
+ mount that is prone to get stuck, or a FUSE mount which cannot
+ be trusted to play fair.
--
-
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