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| author | Coly Li <colyli@suse.de> | 2019-11-13 09:03:24 +0100 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2019-11-13 23:42:50 +0100 |
| commit | 9fcc34b1a6dd4b8e5337e2b6ef45e428897eca6b (patch) | |
| tree | f48581635d520d28d26f7f1cb5969f706c311dab /drivers/md | |
| parent | bcache: add idle_max_writeback_rate sysfs interface (diff) | |
| download | linux-9fcc34b1a6dd4b8e5337e2b6ef45e428897eca6b.tar.xz linux-9fcc34b1a6dd4b8e5337e2b6ef45e428897eca6b.zip | |
bcache: at least try to shrink 1 node in bch_mca_scan()
In bch_mca_scan(), the number of shrinking btree node is calculated
by code like this,
unsigned long nr = sc->nr_to_scan;
nr /= c->btree_pages;
nr = min_t(unsigned long, nr, mca_can_free(c));
variable sc->nr_to_scan is number of objects (here is bcache B+tree
nodes' number) to shrink, and pointer variable sc is sent from memory
management code as parametr of a callback.
If sc->nr_to_scan is smaller than c->btree_pages, after the above
calculation, variable 'nr' will be 0 and nothing will be shrunk. It is
frequeently observed that only 1 or 2 is set to sc->nr_to_scan and make
nr to be zero. Then bch_mca_scan() will do nothing more then acquiring
and releasing mutex c->bucket_lock.
This patch checkes whether nr is 0 after the above calculation, if 0
is the result then set 1 to variable 'n'. Then at least bch_mca_scan()
will try to shrink a single B+tree node.
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'drivers/md')
| -rw-r--r-- | drivers/md/bcache/btree.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c index 48e33ee0d876..3df5fa4a501c 100644 --- a/drivers/md/bcache/btree.c +++ b/drivers/md/bcache/btree.c @@ -754,6 +754,8 @@ static unsigned long bch_mca_scan(struct shrinker *shrink, * IO can always make forward progress: */ nr /= c->btree_pages; + if (nr == 0) + nr = 1; nr = min_t(unsigned long, nr, mca_can_free(c)); i = 0; |