diff options
| -rw-r--r-- | Documentation/ABI/testing/sysfs-class-bdi | 43 | ||||
| -rw-r--r-- | include/linux/backing-dev.h | 6 | ||||
| -rw-r--r-- | mm/backing-dev.c | 98 |
3 files changed, 99 insertions, 48 deletions
diff --git a/Documentation/ABI/testing/sysfs-class-bdi b/Documentation/ABI/testing/sysfs-class-bdi index c55e811ca18..5ac1e01bbd4 100644 --- a/Documentation/ABI/testing/sysfs-class-bdi +++ b/Documentation/ABI/testing/sysfs-class-bdi @@ -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. diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h index ad3271d1e90..c49a2d045e1 100644 --- a/include/linux/backing-dev.h +++ b/include/linux/backing-dev.h @@ -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); diff --git a/mm/backing-dev.c b/mm/backing-dev.c index 08361b6aad5..7c4f9e09709 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -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; } |