On 05/20/2013 12:25 PM, Steven Whitehouse wrote:
> Hi,
>
> On Mon, 2013-05-20 at 00:07 +0400, Glauber Costa wrote:
>> From: Dave Chinner <dchinner@xxxxxxxxxx>
>>
>> Convert the filesystem shrinkers to use the new API, and standardise
>> some of the behaviours of the shrinkers at the same time. For
>> example, nr_to_scan means the number of objects to scan, not the
>> number of objects to free.
>>
>> I refactored the CIFS idmap shrinker a little - it really needs to
>> be broken up into a shrinker per tree and keep an item count with
>> the tree root so that we don't need to walk the tree every time the
>> shrinker needs to count the number of objects in the tree (i.e.
>> all the time under memory pressure).
>>
>> [ glommer: fixes for ext4, ubifs, nfs, cifs and glock. Fixes are
>> needed mainly due to new code merged in the tree ]
>> Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
>> Signed-off-by: Glauber Costa <glommer@xxxxxxxxxx>
>> Acked-by: Mel Gorman <mgorman@xxxxxxx>
>> Acked-by: Artem Bityutskiy <artem.bityutskiy@xxxxxxxxxxxxxxx>
>> Acked-by: Jan Kara <jack@xxxxxxx>
>> CC: Steven Whitehouse <swhiteho@xxxxxxxxxx>
>> CC: Adrian Hunter <adrian.hunter@xxxxxxxxx>
>> ---
>> fs/ext4/extents_status.c | 30 ++++++++++++++++------------
>> fs/gfs2/glock.c | 28 +++++++++++++++-----------
>> fs/gfs2/main.c | 3 ++-
>> fs/gfs2/quota.c | 12 +++++++-----
>> fs/gfs2/quota.h | 4 +++-
>> fs/mbcache.c | 51 ++++++++++++++++++++++++++++--------------------
>> fs/nfs/dir.c | 18 ++++++++++++++---
>> fs/nfs/internal.h | 4 +++-
>> fs/nfs/super.c | 3 ++-
>> fs/nfsd/nfscache.c | 31 ++++++++++++++++++++---------
>> fs/quota/dquot.c | 34 +++++++++++++++-----------------
>> fs/ubifs/shrinker.c | 20 +++++++++++--------
>> fs/ubifs/super.c | 3 ++-
>> fs/ubifs/ubifs.h | 3 ++-
>> 14 files changed, 151 insertions(+), 93 deletions(-)
> [snip]
>> return 0;
>> diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
>> index 3bd2748..4ddbccb 100644
>> --- a/fs/gfs2/glock.c
>> +++ b/fs/gfs2/glock.c
>> @@ -1428,21 +1428,22 @@ __acquires(&lru_lock)
>> * gfs2_dispose_glock_lru() above.
>> */
>>
>> -static void gfs2_scan_glock_lru(int nr)
>> +static long gfs2_scan_glock_lru(int nr)
>> {
>> struct gfs2_glock *gl;
>> LIST_HEAD(skipped);
>> LIST_HEAD(dispose);
>> + long freed = 0;
>>
>> spin_lock(&lru_lock);
>> - while(nr && !list_empty(&lru_list)) {
>> + while ((nr-- >= 0) && !list_empty(&lru_list)) {
>> gl = list_entry(lru_list.next, struct gfs2_glock, gl_lru);
>>
>> /* Test for being demotable */
>> if (!test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
>> list_move(&gl->gl_lru, &dispose);
>> atomic_dec(&lru_count);
>> - nr--;
>> + freed++;
>> continue;
>> }
>>
>
> This seems to change behaviour so that nr is no longer the number of
> items to be demoted, but instead the max number of items to scan in
> order to look for items to be demoted. Does that mean that nr has
> changed its meaning now?
>
> Steve.
>
No, this should be the max number to be demoted, no change.
This test above should then be freed < nr.
I will update, thanks for spotting.
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