scoutfs: add some segment cache life cycle tracing

Signed-off-by: Zach Brown <zab@versity.com>

kmod/src/counters.h

@@ -14,7 +14,9 @@
 #define EXPAND_EACH_COUNTER 		\
 	EXPAND_COUNTER(alloc_alloc)	\
 	EXPAND_COUNTER(alloc_free)	\
-	EXPAND_COUNTER(seg_lru_shrink) \
+	EXPAND_COUNTER(seg_alloc)	\
+	EXPAND_COUNTER(seg_shrink)	\
+	EXPAND_COUNTER(seg_free)	\
 	EXPAND_COUNTER(trans_level0_seg_write) \
 	EXPAND_COUNTER(manifest_compact_migrate) \
 	EXPAND_COUNTER(compact_operations) \

kmod/src/scoutfs_trace.h

@@ -29,6 +29,7 @@
 #include "format.h"
 #include "kvec.h"
 #include "lock.h"
+#include "seg.h"
 
 struct scoutfs_sb_info;
 
@@ -357,6 +358,47 @@ TRACE_EVENT(scoutfs_lock_invalidate_sb,
 		  __get_str(start), __get_str(end))
 );
 
+DECLARE_EVENT_CLASS(scoutfs_seg_class,
+        TP_PROTO(struct scoutfs_segment *seg),
+        TP_ARGS(seg),
+        TP_STRUCT__entry(
+		__field(unsigned int, major)
+		__field(unsigned int, minor)
+		__field(struct scoutfs_segment *, seg)
+		__field(int, refcount)
+		__field(u64, segno)
+		__field(unsigned long, flags)
+		__field(int, err)
+        ),
+        TP_fast_assign(
+		__entry->major = MAJOR(seg->sb->s_bdev->bd_dev);
+		__entry->minor = MINOR(seg->sb->s_bdev->bd_dev);
+		__entry->seg = seg;
+		__entry->refcount = atomic_read(&seg->refcount);
+		__entry->segno = seg->segno;
+		__entry->flags = seg->flags;
+		__entry->err = seg->err;
+        ),
+        TP_printk("dev %u:%u seg %p refcount %d segno %llu flags %lx err %d",
+		  __entry->major, __entry->minor, __entry->seg, __entry->refcount,
+		  __entry->segno, __entry->flags, __entry->err)
+);
+
+DEFINE_EVENT(scoutfs_seg_class, scoutfs_seg_alloc,
+	TP_PROTO(struct scoutfs_segment *seg),
+        TP_ARGS(seg)
+);
+
+DEFINE_EVENT(scoutfs_seg_class, scoutfs_seg_shrink,
+	TP_PROTO(struct scoutfs_segment *seg),
+        TP_ARGS(seg)
+);
+
+DEFINE_EVENT(scoutfs_seg_class, scoutfs_seg_free,
+	TP_PROTO(struct scoutfs_segment *seg),
+        TP_ARGS(seg)
+);
+
 #endif /* _TRACE_SCOUTFS_H */
 
 /* This part must be outside protection */

kmod/src/seg.c

@@ -26,6 +26,7 @@
 #include "alloc.h"
 #include "key.h"
 #include "counters.h"
+#include "scoutfs_trace.h"
 
 /*
  * seg.c should just be about the cache and io, and maybe
@@ -49,21 +50,12 @@ struct segment_cache {
 	unsigned long lru_nr;
 };
 
-struct scoutfs_segment {
-	struct rb_node node;
-	struct list_head lru_entry;
-	atomic_t refcount;
-	u64 segno;
-	unsigned long flags;
-	int err;
-	struct page *pages[SCOUTFS_SEGMENT_PAGES];
-};
 
 enum {
 	SF_END_IO = 0,
 };
 
-static struct scoutfs_segment *alloc_seg(u64 segno)
+static struct scoutfs_segment *alloc_seg(struct super_block *sb, u64 segno)
 {
 	struct scoutfs_segment *seg;
 	struct page *page;
@@ -76,6 +68,7 @@ static struct scoutfs_segment *alloc_seg(u64 segno)
 	if (!seg)
 		return seg;
 
+	seg->sb = sb;
 	RB_CLEAR_NODE(&seg->node);
 	INIT_LIST_HEAD(&seg->lru_entry);
 	atomic_set(&seg->refcount, 1);
@@ -83,8 +76,6 @@ static struct scoutfs_segment *alloc_seg(u64 segno)
 
 	for (i = 0; i < SCOUTFS_SEGMENT_PAGES; i++) {
 		page = alloc_page(GFP_NOFS);
-		trace_printk("seg %p segno %llu page %u %p\n",
-			     seg, segno, i, page);
 		if (!page) {
 			scoutfs_seg_put(seg);
 			return ERR_PTR(-ENOMEM);
@@ -93,6 +84,9 @@ static struct scoutfs_segment *alloc_seg(u64 segno)
 		seg->pages[i] = page;
 	}
 
+	trace_scoutfs_seg_alloc(seg);
+	scoutfs_inc_counter(sb, seg_alloc);
+
 	return seg;
 }
 
@@ -106,6 +100,8 @@ void scoutfs_seg_put(struct scoutfs_segment *seg)
 	int i;
 
 	if (!IS_ERR_OR_NULL(seg) && atomic_dec_and_test(&seg->refcount)) {
+		trace_scoutfs_seg_free(seg);
+		scoutfs_inc_counter(seg->sb, seg_free);
 		WARN_ON_ONCE(!RB_EMPTY_NODE(&seg->node));
 		WARN_ON_ONCE(!list_empty(&seg->lru_entry));
 		for (i = 0; i < SCOUTFS_SEGMENT_PAGES; i++)
@@ -256,7 +252,7 @@ int scoutfs_seg_alloc(struct super_block *sb, u64 segno,
 	unsigned long flags;
 	int ret;
 
-	seg = alloc_seg(segno);
+	seg = alloc_seg(sb, segno);
 	if (!seg) {
 		ret = -ENOMEM;
 		goto out;
@@ -321,7 +317,7 @@ struct scoutfs_segment *scoutfs_seg_submit_read(struct super_block *sb,
 	if (seg)
 		return seg;
 
-	seg = alloc_seg(segno);
+	seg = alloc_seg(sb, segno);
 	if (IS_ERR(seg))
 		return seg;
 
@@ -776,7 +772,8 @@ static int seg_lru_shrink(struct shrinker *shrink, struct shrink_control *sc)
 	spin_unlock_irqrestore(&cac->lock, flags);
 
 	list_for_each_entry_safe(seg, tmp, &list, lru_entry) {
-		scoutfs_inc_counter(sb, seg_lru_shrink);
+		trace_scoutfs_seg_shrink(seg);
+		scoutfs_inc_counter(sb, seg_shrink);
 		list_del_init(&seg->lru_entry);
 		scoutfs_seg_put(seg);
 	}

kmod/src/seg.h

@@ -2,10 +2,21 @@
 #define _SCOUTFS_SEG_H_
 
 struct scoutfs_bio_completion;
-struct scoutfs_segment;
 struct scoutfs_key_buf;
 struct kvec;
 
+/* this is only visible for trace events */
+struct scoutfs_segment {
+	struct super_block *sb;
+	struct rb_node node;
+	struct list_head lru_entry;
+	atomic_t refcount;
+	u64 segno;
+	unsigned long flags;
+	int err;
+	struct page *pages[SCOUTFS_SEGMENT_PAGES];
+};
+
 struct scoutfs_segment *scoutfs_seg_submit_read(struct super_block *sb,
 						u64 segno);
 int scoutfs_seg_wait(struct super_block *sb, struct scoutfs_segment *seg);