linux-toradex.git/fs/drop_caches.c, branch v4.5

inode: convert inode_sb_list_lock to per-sb

2015-08-17T22:39:46+00:00

The process of reducing contention on per-superblock inode lists
starts with moving the locking to match the per-superblock inode
list. This takes the global lock out of the picture and reduces the
contention problems to within a single filesystem. This doesn't get
rid of contention as the locks still have global CPU scope, but it
does isolate operations on different superblocks form each other.

Signed-off-by: Dave Chinner 
Signed-off-by: Josef Bacik 
Reviewed-by: Jan Kara 
Reviewed-by: Christoph Hellwig 
Tested-by: Dave Chinner

vmscan: per memory cgroup slab shrinkers

2015-02-13T02:54:09+00:00

This patch adds SHRINKER_MEMCG_AWARE flag.  If a shrinker has this flag
set, it will be called per memory cgroup.  The memory cgroup to scan
objects from is passed in shrink_control->memcg.  If the memory cgroup
is NULL, a memcg aware shrinker is supposed to scan objects from the
global list.  Unaware shrinkers are only called on global pressure with
memcg=NULL.

Signed-off-by: Vladimir Davydov 
Cc: Dave Chinner 
Cc: Johannes Weiner 
Cc: Michal Hocko 
Cc: Greg Thelen 
Cc: Glauber Costa 
Cc: Alexander Viro 
Cc: Christoph Lameter 
Cc: Pekka Enberg 
Cc: David Rientjes 
Cc: Joonsoo Kim 
Cc: Tejun Heo 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: vmscan: invoke slab shrinkers from shrink_zone()

2014-12-13T20:42:48+00:00

The slab shrinkers are currently invoked from the zonelist walkers in
kswapd, direct reclaim, and zone reclaim, all of which roughly gauge the
eligible LRU pages and assemble a nodemask to pass to NUMA-aware
shrinkers, which then again have to walk over the nodemask.  This is
redundant code, extra runtime work, and fairly inaccurate when it comes to
the estimation of actually scannable LRU pages.  The code duplication will
only get worse when making the shrinkers cgroup-aware and requiring them
to have out-of-band cgroup hierarchy walks as well.

Instead, invoke the shrinkers from shrink_zone(), which is where all
reclaimers end up, to avoid this duplication.

Take the count for eligible LRU pages out of get_scan_count(), which
considers many more factors than just the availability of swap space, like
zone_reclaimable_pages() currently does.  Accumulate the number over all
visited lruvecs to get the per-zone value.

Some nodes have multiple zones due to memory addressing restrictions.  To
avoid putting too much pressure on the shrinkers, only invoke them once
for each such node, using the class zone of the allocation as the pivot
zone.

For now, this integrates the slab shrinking better into the reclaim logic
and gets rid of duplicative invocations from kswapd, direct reclaim, and
zone reclaim.  It also prepares for cgroup-awareness, allowing
memcg-capable shrinkers to be added at the lruvec level without much
duplication of both code and runtime work.

This changes kswapd behavior, which used to invoke the shrinkers for each
zone, but with scan ratios gathered from the entire node, resulting in
meaningless pressure quantities on multi-zone nodes.

Zone reclaim behavior also changes.  It used to shrink slabs until the
same amount of pages were shrunk as were reclaimed from the LRUs.  Now it
merely invokes the shrinkers once with the zone's scan ratio, which makes
the shrinkers go easier on caches that implement aging and would prefer
feeding back pressure from recently used slab objects to unused LRU pages.

[vdavydov@parallels.com: assure class zone is populated]
Signed-off-by: Johannes Weiner 
Cc: Dave Chinner 
Signed-off-by: Vladimir Davydov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

fs: convert use of typedef ctl_table to struct ctl_table

2014-06-06T23:08:16+00:00

This typedef is unnecessary and should just be removed.

Signed-off-by: Joe Perches 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

drop_caches: add some documentation and info message

2014-04-03T23:21:04+00:00

There is plenty of anecdotal evidence and a load of blog posts
suggesting that using "drop_caches" periodically keeps your system
running in "tip top shape".  Perhaps adding some kernel documentation
will increase the amount of accurate data on its use.

If we are not shrinking caches effectively, then we have real bugs.
Using drop_caches will simply mask the bugs and make them harder to
find, but certainly does not fix them, nor is it an appropriate
"workaround" to limit the size of the caches.  On the contrary, there
have been bug reports on issues that turned out to be misguided use of
cache dropping.

Dropping caches is a very drastic and disruptive operation that is good
for debugging and running tests, but if it creates bug reports from
production use, kernel developers should be aware of its use.

Add a bit more documentation about it, a syslog message to track down
abusers, and vmstat drop counters to help analyze problem reports.

[akpm@linux-foundation.org: checkpatch fixes]
[hannes@cmpxchg.org: add runtime suppression control]
Signed-off-by: Dave Hansen 
Signed-off-by: Michal Hocko 
Acked-by: KOSAKI Motohiro 
Acked-by: KAMEZAWA Hiroyuki 
Signed-off-by: Johannes Weiner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

shrinker: add node awareness

2013-09-10T22:56:31+00:00

Pass the node of the current zone being reclaimed to shrink_slab(),
allowing the shrinker control nodemask to be set appropriately for node
aware shrinkers.

Signed-off-by: Dave Chinner 
Signed-off-by: Glauber Costa 
Acked-by: Mel Gorman 
Cc: "Theodore Ts'o" 
Cc: Adrian Hunter 
Cc: Al Viro 
Cc: Artem Bityutskiy 
Cc: Arve Hjønnevåg 
Cc: Carlos Maiolino 
Cc: Christoph Hellwig 
Cc: Chuck Lever 
Cc: Daniel Vetter 
Cc: David Rientjes 
Cc: Gleb Natapov 
Cc: Greg Thelen 
Cc: J. Bruce Fields 
Cc: Jan Kara 
Cc: Jerome Glisse 
Cc: John Stultz 
Cc: KAMEZAWA Hiroyuki 
Cc: Kent Overstreet 
Cc: Kirill A. Shutemov 
Cc: Marcelo Tosatti 
Cc: Mel Gorman 
Cc: Steven Whitehouse 
Cc: Thomas Hellstrom 
Cc: Trond Myklebust 
Signed-off-by: Andrew Morton 
Signed-off-by: Al Viro

vmscan: change shrinker API by passing shrink_control struct

2011-05-25T15:39:26+00:00

Change each shrinker's API by consolidating the existing parameters into
shrink_control struct.  This will simplify any further features added w/o
touching each file of shrinker.

[akpm@linux-foundation.org: fix build]
[akpm@linux-foundation.org: fix warning]
[kosaki.motohiro@jp.fujitsu.com: fix up new shrinker API]
[akpm@linux-foundation.org: fix xfs warning]
[akpm@linux-foundation.org: update gfs2]
Signed-off-by: Ying Han 
Cc: KOSAKI Motohiro 
Cc: Minchan Kim 
Acked-by: Pavel Emelyanov 
Cc: KAMEZAWA Hiroyuki 
Cc: Mel Gorman 
Acked-by: Rik van Riel 
Cc: Johannes Weiner 
Cc: Hugh Dickins 
Cc: Dave Hansen 
Cc: Steven Whitehouse 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

vmscan: change shrink_slab() interfaces by passing shrink_control

2011-05-25T15:39:25+00:00

Consolidate the existing parameters to shrink_slab() into a new
shrink_control struct.  This is needed later to pass the same struct to
shrinkers.

Signed-off-by: Ying Han 
Cc: KOSAKI Motohiro 
Cc: Minchan Kim 
Acked-by: Pavel Emelyanov 
Cc: KAMEZAWA Hiroyuki 
Cc: Mel Gorman 
Acked-by: Rik van Riel 
Cc: Johannes Weiner 
Cc: Hugh Dickins 
Cc: Dave Hansen 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

fs: move i_sb_list out from under inode_lock

2011-03-25T01:16:32+00:00

Protect the per-sb inode list with a new global lock
inode_sb_list_lock and use it to protect the list manipulations and
traversals. This lock replaces the inode_lock as the inodes on the
list can be validity checked while holding the inode->i_lock and
hence the inode_lock is no longer needed to protect the list.

Signed-off-by: Dave Chinner 
Signed-off-by: Al Viro

fs: protect inode->i_state with inode->i_lock

2011-03-25T01:16:31+00:00

Protect inode state transitions and validity checks with the
inode->i_lock. This enables us to make inode state transitions
independently of the inode_lock and is the first step to peeling
away the inode_lock from the code.

This requires that __iget() is done atomically with i_state checks
during list traversals so that we don't race with another thread
marking the inode I_FREEING between the state check and grabbing the
reference.

Also remove the unlock_new_inode() memory barrier optimisation
required to avoid taking the inode_lock when clearing I_NEW.
Simplify the code by simply taking the inode->i_lock around the
state change and wakeup. Because the wakeup is no longer tricky,
remove the wake_up_inode() function and open code the wakeup where
necessary.

Signed-off-by: Dave Chinner 
Signed-off-by: Al Viro