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Commit 76f1418b authored by Miklos Szeredi's avatar Miklos Szeredi Committed by Linus Torvalds
Browse files

mm: bdi: move statistics to debugfs 



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: default avatarMiklos Szeredi <mszeredi@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a42dde04

Documentation/ABI/testing/sysfs-class-bdi

+15 −28
Original line number Diff line number Diff line
@@ -3,8 +3,8 @@ Date: January 2008 
Contact:	Peter Zijlstra <a.p.zijlstra@chello.nl>

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.

include/linux/backing-dev.h

+6 −0
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ 


struct page;

struct device;

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);

mm/backing-dev.c

+78 −20
Original line number Diff line number Diff line
@@ -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 *dev, \ 


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, struct device *parent, 


	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;

	}