GFS2: Automatically adjust glock min hold time

This patch is a performance improvement for GFS2 in a clustered
environment. It makes the glock hold time self-adjusting.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

4 files changed, 36 insertions, 13 deletions

diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 1c1336e7b3b2..88e8a23d0026 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -409,6 +409,10 @@ static void state_change(struct gfs2_glock *gl, unsigned int new_state)
         if (held1 && held2 && list_empty(&gl->gl_holders))
                 clear_bit(GLF_QUEUED, &gl->gl_flags);
 
+        if (new_state != gl->gl_target)
+                /* shorten our minimum hold time */
+                gl->gl_hold_time = max(gl->gl_hold_time - GL_GLOCK_HOLD_DECR,
+                                       GL_GLOCK_MIN_HOLD);
         gl->gl_state = new_state;
         gl->gl_tchange = jiffies;
 }
@@ -668,7 +672,7 @@ static void glock_work_func(struct work_struct *work)
             gl->gl_demote_state != LM_ST_EXCLUSIVE) {
                 unsigned long holdtime, now = jiffies;
 
-                holdtime = gl->gl_tchange + gl->gl_ops->go_min_hold_time;
+                holdtime = gl->gl_tchange + gl->gl_hold_time;
                 if (time_before(now, holdtime))
                         delay = holdtime - now;
 
@@ -679,9 +683,14 @@ static void glock_work_func(struct work_struct *work)
         }
         run_queue(gl, 0);
         spin_unlock(&gl->gl_spin);
-        if (!delay ||
-            queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
+        if (!delay)
                 gfs2_glock_put(gl);
+        else {
+                if (gl->gl_name.ln_type != LM_TYPE_INODE)
+                        delay = 0;
+                if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
+                        gfs2_glock_put(gl);
+        }
         if (drop_ref)
                 gfs2_glock_put(gl);
 }
@@ -743,6 +752,7 @@ int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
         gl->gl_tchange = jiffies;
         gl->gl_object = NULL;
         gl->gl_sbd = sdp;
+        gl->gl_hold_time = GL_GLOCK_DFT_HOLD;
         INIT_DELAYED_WORK(&gl->gl_work, glock_work_func);
         INIT_WORK(&gl->gl_delete, delete_work_func);
 
@@ -855,8 +865,15 @@ static int gfs2_glock_demote_wait(void *word)
 
 static void wait_on_holder(struct gfs2_holder *gh)
 {
+        unsigned long time1 = jiffies;
+
         might_sleep();
         wait_on_bit(&gh->gh_iflags, HIF_WAIT, gfs2_glock_holder_wait, TASK_UNINTERRUPTIBLE);
+        if (time_after(jiffies, time1 + HZ)) /* have we waited > a second? */
+                /* Lengthen the minimum hold time. */
+                gh->gh_gl->gl_hold_time = min(gh->gh_gl->gl_hold_time +
+                                              GL_GLOCK_HOLD_INCR,
+                                              GL_GLOCK_MAX_HOLD);
 }
 
 static void wait_on_demote(struct gfs2_glock *gl)
@@ -1093,8 +1110,9 @@ void gfs2_glock_dq(struct gfs2_holder *gh)
 
         gfs2_glock_hold(gl);
         if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
-            !test_bit(GLF_DEMOTE, &gl->gl_flags))
-                delay = gl->gl_ops->go_min_hold_time;
+            !test_bit(GLF_DEMOTE, &gl->gl_flags) &&
+            gl->gl_name.ln_type == LM_TYPE_INODE)
+                delay = gl->gl_hold_time;
         if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
                 gfs2_glock_put(gl);
 }
@@ -1273,12 +1291,13 @@ void gfs2_glock_cb(struct gfs2_glock *gl, unsigned int state)
         unsigned long now = jiffies;
 
         gfs2_glock_hold(gl);
-        holdtime = gl->gl_tchange + gl->gl_ops->go_min_hold_time;
-        if (test_bit(GLF_QUEUED, &gl->gl_flags)) {
+        holdtime = gl->gl_tchange + gl->gl_hold_time;
+        if (test_bit(GLF_QUEUED, &gl->gl_flags) &&
+            gl->gl_name.ln_type == LM_TYPE_INODE) {
                 if (time_before(now, holdtime))
                         delay = holdtime - now;
                 if (test_bit(GLF_REPLY_PENDING, &gl->gl_flags))
-                        delay = gl->gl_ops->go_min_hold_time;
+                        delay = gl->gl_hold_time;
         }
 
         spin_lock(&gl->gl_spin);
@@ -1667,7 +1686,7 @@ static int __dump_glock(struct seq_file *seq, const struct gfs2_glock *gl)
         dtime *= 1000000/HZ; /* demote time in uSec */
         if (!test_bit(GLF_DEMOTE, &gl->gl_flags))
                 dtime = 0;
-        gfs2_print_dbg(seq, "G:  s:%s n:%u/%llx f:%s t:%s d:%s/%llu a:%d v:%d r:%d\n",
+        gfs2_print_dbg(seq, "G:  s:%s n:%u/%llx f:%s t:%s d:%s/%llu a:%d v:%d r:%d m:%ld\n",
                   state2str(gl->gl_state),
                   gl->gl_name.ln_type,
                   (unsigned long long)gl->gl_name.ln_number,
@@ -1676,7 +1695,7 @@ static int __dump_glock(struct seq_file *seq, const struct gfs2_glock *gl)
                   state2str(gl->gl_demote_state), dtime,
                   atomic_read(&gl->gl_ail_count),
                   atomic_read(&gl->gl_revokes),
-                  atomic_read(&gl->gl_ref));
+                  atomic_read(&gl->gl_ref), gl->gl_hold_time);
 
         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
                 error = dump_holder(seq, gh);
diff --git a/fs/gfs2/glock.h b/fs/gfs2/glock.h
index 6b2f757b9281..66707118af25 100644
--- a/fs/gfs2/glock.h
+++ b/fs/gfs2/glock.h
@@ -113,6 +113,12 @@ enum {
 
 #define GLR_TRYFAILED           13
 
+#define GL_GLOCK_MAX_HOLD        (long)(HZ / 5)
+#define GL_GLOCK_DFT_HOLD        (long)(HZ / 5)
+#define GL_GLOCK_MIN_HOLD        (long)(10)
+#define GL_GLOCK_HOLD_INCR       (long)(HZ / 20)
+#define GL_GLOCK_HOLD_DECR       (long)(HZ / 40)
+
 struct lm_lockops {
         const char *lm_proto_name;
         int (*lm_mount) (struct gfs2_sbd *sdp, const char *fsname);
diff --git a/fs/gfs2/glops.c b/fs/gfs2/glops.c
index 95788ae436c6..a4222c3f5993 100644
--- a/fs/gfs2/glops.c
+++ b/fs/gfs2/glops.c
@@ -551,7 +551,6 @@ const struct gfs2_glock_operations gfs2_inode_glops = {
         .go_lock = inode_go_lock,
         .go_dump = inode_go_dump,
         .go_type = LM_TYPE_INODE,
-        .go_min_hold_time = HZ / 5,
         .go_flags = GLOF_ASPACE,
 };
 
@@ -562,7 +561,6 @@ const struct gfs2_glock_operations gfs2_rgrp_glops = {
         .go_unlock = rgrp_go_unlock,
         .go_dump = gfs2_rgrp_dump,
         .go_type = LM_TYPE_RGRP,
-        .go_min_hold_time = HZ / 5,
         .go_flags = GLOF_ASPACE,
 };
 
diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h
index 24cd55f60e60..892ac37de8ae 100644
--- a/fs/gfs2/incore.h
+++ b/fs/gfs2/incore.h
@@ -163,7 +163,6 @@ struct gfs2_glock_operations {
         int (*go_dump)(struct seq_file *seq, const struct gfs2_glock *gl);
         void (*go_callback) (struct gfs2_glock *gl);
         const int go_type;
-        const unsigned long go_min_hold_time;
         const unsigned long go_flags;
 #define GLOF_ASPACE 1
 };
@@ -221,6 +220,7 @@ struct gfs2_glock {
 
         unsigned int gl_hash;
         unsigned long gl_demote_time; /* time of first demote request */
+        long gl_hold_time;
         struct list_head gl_holders;
 
         const struct gfs2_glock_operations *gl_ops;