Hi,
The comment for struct shrinker in include/linux/mm.h says
"shrink...It should return the number of objects which remain in the
cache."
Please notice the word "remain".
In fs/mbcache.h, mb_cache_shrink_fn is used as the shrink function:
static struct shrinker mb_cache_shrinker = {
.shrink = mb_cache_shrink_fn,
.seeks = DEFAULT_SEEKS,
};
In mb_cache_shrink_fn, the return value for nr_to_scan > 0 is the
number of mb_cache_entry before shrink operation. It may because the
memory usage for mbcache is low, so the effect is not so obvious.
I think we'd better fix the return value issue.
Following patch is against 2.6.35-rc5. Please check it.
Signed-off-by: Wang Sheng-Hui <crosslonelyover@xxxxxxxxx>
---
fs/mbcache.c | 10 ++++++++++
1 files changed, 10 insertions(+), 0 deletions(-)
diff --git a/fs/mbcache.c b/fs/mbcache.c
index ec88ff3..412e7cc 100644
--- a/fs/mbcache.c
+++ b/fs/mbcache.c
@@ -228,6 +228,16 @@ mb_cache_shrink_fn(int nr_to_scan, gfp_t gfp_mask)
__mb_cache_entry_forget(list_entry(l, struct mb_cache_entry,
e_lru_list), gfp_mask);
}
+ spin_lock(&mb_cache_spinlock);
+ count = 0;
+ list_for_each(l, &mb_cache_list) {
+ struct mb_cache *cache =
+ list_entry(l, struct mb_cache, c_cache_list);
+ mb_debug("cache %s (%d)", cache->c_name,
+ atomic_read(&cache->c_entry_count));
+ count += atomic_read(&cache->c_entry_count);
+ }
+ spin_unlock(&mb_cache_spinlock);
out:
return (count / 100) * sysctl_vfs_cache_pressure;
}
--
1.7.1.1
--
Thanks and Regards,
shenghui
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