Commit 55f841ce authored Aug 28, 2013 by Glauber Costa Committed by Al Viro Sep 10, 2013

super: fix calculation of shrinkable objects for small numbers



The sysctl knob sysctl_vfs_cache_pressure is used to determine which
percentage of the shrinkable objects in our cache we should actively try
to shrink.

It works great in situations in which we have many objects (at least more
than 100), because the aproximation errors will be negligible.  But if
this is not the case, specially when total_objects < 100, we may end up
concluding that we have no objects at all (total / 100 = 0, if total <
100).

This is certainly not the biggest killer in the world, but may matter in
very low kernel memory situations.

Signed-off-by: Glauber Costa <glommer@openvz.org>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Cc: Arve Hjønnevåg <arve@android.com>
Cc: Carlos Maiolino <cmaiolino@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: David Rientjes <rientjes@google.com>
Cc: Gleb Natapov <gleb@redhat.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: J. Bruce Fields <bfields@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Kent Overstreet <koverstreet@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Thomas Hellstrom <thellstrom@vmware.com>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

parent 3942c07c

fs/gfs2/glock.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -1462,7 +1462,7 @@ static int gfs2_shrink_glock_memory(struct shrinker *shrink,
		gfs2_scan_glock_lru(sc->nr_to_scan);
		}

		return (atomic_read(&lru_count) / 100) * sysctl_vfs_cache_pressure;
		return vfs_pressure_ratio(atomic_read(&lru_count));
		}

		static struct shrinker glock_shrinker = {

fs/gfs2/quota.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -114,7 +114,7 @@ int gfs2_shrink_qd_memory(struct shrinker shrink, struct shrink_control sc)
		spin_unlock(&qd_lru_lock);

		out:
		return (atomic_read(&qd_lru_count) * sysctl_vfs_cache_pressure) / 100;
		return vfs_pressure_ratio(atomic_read(&qd_lru_count));
		}

		static u64 qd2index(struct gfs2_quota_data *qd)

fs/mbcache.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -189,7 +189,7 @@ mb_cache_shrink_fn(struct shrinker shrink, struct shrink_control sc)
		list_for_each_entry_safe(entry, tmp, &free_list, e_lru_list) {
		__mb_cache_entry_forget(entry, gfp_mask);
		}
		return (count / 100) * sysctl_vfs_cache_pressure;
		return vfs_pressure_ratio(count);
		}

fs/nfs/dir.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -2046,7 +2046,7 @@ remove_lru_entry:
		}
		spin_unlock(&nfs_access_lru_lock);
		nfs_access_free_list(&head);
		return (atomic_long_read(&nfs_access_nr_entries) / 100) * sysctl_vfs_cache_pressure;
		return vfs_pressure_ratio(atomic_long_read(&nfs_access_nr_entries));
		}

		static void __nfs_access_zap_cache(struct nfs_inode nfsi, struct list_head head)

fs/quota/dquot.c

+2 −3

Original line number	Diff line number	Diff line
		@@ -719,9 +719,8 @@ static int shrink_dqcache_memory(struct shrinker *shrink,
		prune_dqcache(nr);
		spin_unlock(&dq_list_lock);
		}
		return ((unsigned)
		percpu_counter_read_positive(&dqstats.counter[DQST_FREE_DQUOTS])
		/100) * sysctl_vfs_cache_pressure;
		return vfs_pressure_ratio(
		percpu_counter_read_positive(&dqstats.counter[DQST_FREE_DQUOTS]));
		}

		static struct shrinker dqcache_shrinker = {

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