dlm: avoid scanning unchanged toss lists

Keep track of whether a toss list contains any
shrinkable rsbs.  If not, dlm_scand can avoid
scanning the list for rsbs to shrink.  Unnecessary
scanning can otherwise waste a lot of time because
the toss lists can contain a large number of rsbs
that are non-shrinkable (directory records).

Signed-off-by: David Teigland <teigland@redhat.com>

diff --git a/fs/dlm/dlm_internal.h b/fs/dlm/dlm_internal.h
index 77c0f70..e7665c3 100644 (file)
--- a/fs/dlm/dlm_internal.h
+++ b/fs/dlm/dlm_internal.h
@@ -96,10 +96,13 @@ do { \
 }
 
 
+#define DLM_RTF_SHRINK         0x00000001
+
 struct dlm_rsbtable {
        struct rb_root          keep;
        struct rb_root          toss;
        spinlock_t              lock;
+       uint32_t                flags;
 };
 
 

diff --git a/fs/dlm/lock.c b/fs/dlm/lock.c
index a579f30..f750165 100644 (file)
--- a/fs/dlm/lock.c
+++ b/fs/dlm/lock.c
@@ -1132,6 +1132,7 @@ static void toss_rsb(struct kref *kref)
        rb_erase(&r->res_hashnode, &ls->ls_rsbtbl[r->res_bucket].keep);
        rsb_insert(r, &ls->ls_rsbtbl[r->res_bucket].toss);
        r->res_toss_time = jiffies;
+       ls->ls_rsbtbl[r->res_bucket].flags |= DLM_RTF_SHRINK;
        if (r->res_lvbptr) {
                dlm_free_lvb(r->res_lvbptr);
                r->res_lvbptr = NULL;
@@ -1659,11 +1660,18 @@ static void shrink_bucket(struct dlm_ls *ls, int b)
        char *name;
        int our_nodeid = dlm_our_nodeid();
        int remote_count = 0;
+       int need_shrink = 0;
        int i, len, rv;
 
        memset(&ls->ls_remove_lens, 0, sizeof(int) * DLM_REMOVE_NAMES_MAX);
 
        spin_lock(&ls->ls_rsbtbl[b].lock);
+
+       if (!(ls->ls_rsbtbl[b].flags & DLM_RTF_SHRINK)) {
+               spin_unlock(&ls->ls_rsbtbl[b].lock);
+               return;
+       }
+
        for (n = rb_first(&ls->ls_rsbtbl[b].toss); n; n = next) {
                next = rb_next(n);
                r = rb_entry(n, struct dlm_rsb, res_hashnode);
@@ -1679,6 +1687,8 @@ static void shrink_bucket(struct dlm_ls *ls, int b)
                        continue;
                }
 
+               need_shrink = 1;
+
                if (!time_after_eq(jiffies, r->res_toss_time +
                                   dlm_config.ci_toss_secs * HZ)) {
                        continue;
@@ -1710,6 +1720,11 @@ static void shrink_bucket(struct dlm_ls *ls, int b)
                rb_erase(&r->res_hashnode, &ls->ls_rsbtbl[b].toss);
                dlm_free_rsb(r);
        }
+
+       if (need_shrink)
+               ls->ls_rsbtbl[b].flags |= DLM_RTF_SHRINK;
+       else
+               ls->ls_rsbtbl[b].flags &= ~DLM_RTF_SHRINK;
        spin_unlock(&ls->ls_rsbtbl[b].lock);
 
        /*