| Message ID | 20240824191020.3170516-11-kent.overstreet@linux.dev (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | shrinker debugging, .to_text() report (resend) | expand |
On Sat, Aug 24, 2024 at 03:10:17PM -0400, Kent Overstreet wrote: > Implement shrinker.to_text() for the superblock shrinker: print out nr > of dentries and inodes, total and shrinkable. > > Cc: Alexander Viro <viro@zeniv.linux.org.uk> > Cc: Christian Brauner <brauner@kernel.org> > Cc: Dave Chinner <david@fromorbit.com> > Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev> > --- > fs/super.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/fs/super.c b/fs/super.c > index 5b0fea6ff1cd..d3e43127e311 100644 > --- a/fs/super.c > +++ b/fs/super.c > @@ -36,6 +36,7 @@ > #include <linux/lockdep.h> > #include <linux/user_namespace.h> > #include <linux/fs_context.h> > +#include <linux/seq_buf.h> > #include <uapi/linux/mount.h> > #include "internal.h" > > @@ -270,6 +271,16 @@ static unsigned long super_cache_count(struct shrinker *shrink, > return total_objects; > } > > +static void super_cache_to_text(struct seq_buf *out, struct shrinker *shrink) > +{ > + struct super_block *sb = shrink->private_data; > + > + seq_buf_printf(out, "inodes: total %zu shrinkable %lu\n", > + per_cpu_sum(sb->s_inodes_nr), list_lru_count(&sb->s_inode_lru)); > + seq_buf_printf(out, "dentries: toal %zu shrinkbale %lu\n", > + per_cpu_sum(sb->s_dentry_nr), list_lru_count(&sb->s_dentry_lru)); There's no superblock identification in this output - how are we supposed to take this information and relate it to the filesystems that are mounted on the system? Also, list_lru_count() only counts root memcg objects, so any inodes and dentries accounted to memcgs and are freeable will not be included in this output. For systems with lots of memcgs, that will result in the superblock reporting lots of inodes and dentries, but almost nothing being freeable. hence to do this correctly, there needs to be per-node, per-memcg list_lru_count_one() iteration here... -Dave.
diff --git a/fs/super.c b/fs/super.c index 5b0fea6ff1cd..d3e43127e311 100644 --- a/fs/super.c +++ b/fs/super.c @@ -36,6 +36,7 @@ #include <linux/lockdep.h> #include <linux/user_namespace.h> #include <linux/fs_context.h> +#include <linux/seq_buf.h> #include <uapi/linux/mount.h> #include "internal.h" @@ -270,6 +271,16 @@ static unsigned long super_cache_count(struct shrinker *shrink, return total_objects; } +static void super_cache_to_text(struct seq_buf *out, struct shrinker *shrink) +{ + struct super_block *sb = shrink->private_data; + + seq_buf_printf(out, "inodes: total %zu shrinkable %lu\n", + per_cpu_sum(sb->s_inodes_nr), list_lru_count(&sb->s_inode_lru)); + seq_buf_printf(out, "dentries: toal %zu shrinkbale %lu\n", + per_cpu_sum(sb->s_dentry_nr), list_lru_count(&sb->s_dentry_lru)); +} + static void destroy_super_work(struct work_struct *work) { struct super_block *s = container_of(work, struct super_block, @@ -394,6 +405,7 @@ static struct super_block *alloc_super(struct file_system_type *type, int flags, s->s_shrink->scan_objects = super_cache_scan; s->s_shrink->count_objects = super_cache_count; + s->s_shrink->to_text = super_cache_to_text; s->s_shrink->batch = 1024; s->s_shrink->private_data = s;
Implement shrinker.to_text() for the superblock shrinker: print out nr of dentries and inodes, total and shrinkable. Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Christian Brauner <brauner@kernel.org> Cc: Dave Chinner <david@fromorbit.com> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev> --- fs/super.c | 12 ++++++++++++ 1 file changed, 12 insertions(+)