2 files changed, 137 insertions, 0 deletions

diff --git a/tools/perf/util/auxtrace.c b/tools/perf/util/auxtrace.c
index c4515e1a9d7f..3cd89eca1e88 100644
--- a/tools/perf/util/auxtrace.c
+++ b/tools/perf/util/auxtrace.c
@@ -40,6 +40,8 @@
 #include "asm/bug.h"
 #include "auxtrace.h"
 
+#include <linux/hash.h>
+
 #include "event.h"
 #include "session.h"
 #include "debug.h"
@@ -944,3 +946,124 @@ int auxtrace_mmap__read(struct auxtrace_mmap *mm, struct auxtrace_record *itr,
 
         return 1;
 }
+
+/**
+ * struct auxtrace_cache - hash table to implement a cache
+ * @hashtable: the hashtable
+ * @sz: hashtable size (number of hlists)
+ * @entry_size: size of an entry
+ * @limit: limit the number of entries to this maximum, when reached the cache
+ *         is dropped and caching begins again with an empty cache
+ * @cnt: current number of entries
+ * @bits: hashtable size (@sz = 2^@bits)
+ */
+struct auxtrace_cache {
+        struct hlist_head *hashtable;
+        size_t sz;
+        size_t entry_size;
+        size_t limit;
+        size_t cnt;
+        unsigned int bits;
+};
+
+struct auxtrace_cache *auxtrace_cache__new(unsigned int bits, size_t entry_size,
+                                           unsigned int limit_percent)
+{
+        struct auxtrace_cache *c;
+        struct hlist_head *ht;
+        size_t sz, i;
+
+        c = zalloc(sizeof(struct auxtrace_cache));
+        if (!c)
+                return NULL;
+
+        sz = 1UL << bits;
+
+        ht = calloc(sz, sizeof(struct hlist_head));
+        if (!ht)
+                goto out_free;
+
+        for (i = 0; i < sz; i++)
+                INIT_HLIST_HEAD(&ht[i]);
+
+        c->hashtable = ht;
+        c->sz = sz;
+        c->entry_size = entry_size;
+        c->limit = (c->sz * limit_percent) / 100;
+        c->bits = bits;
+
+        return c;
+
+out_free:
+        free(c);
+        return NULL;
+}
+
+static void auxtrace_cache__drop(struct auxtrace_cache *c)
+{
+        struct auxtrace_cache_entry *entry;
+        struct hlist_node *tmp;
+        size_t i;
+
+        if (!c)
+                return;
+
+        for (i = 0; i < c->sz; i++) {
+                hlist_for_each_entry_safe(entry, tmp, &c->hashtable[i], hash) {
+                        hlist_del(&entry->hash);
+                        auxtrace_cache__free_entry(c, entry);
+                }
+        }
+
+        c->cnt = 0;
+}
+
+void auxtrace_cache__free(struct auxtrace_cache *c)
+{
+        if (!c)
+                return;
+
+        auxtrace_cache__drop(c);
+        free(c->hashtable);
+        free(c);
+}
+
+void *auxtrace_cache__alloc_entry(struct auxtrace_cache *c)
+{
+        return malloc(c->entry_size);
+}
+
+void auxtrace_cache__free_entry(struct auxtrace_cache *c __maybe_unused,
+                                void *entry)
+{
+        free(entry);
+}
+
+int auxtrace_cache__add(struct auxtrace_cache *c, u32 key,
+                        struct auxtrace_cache_entry *entry)
+{
+        if (c->limit && ++c->cnt > c->limit)
+                auxtrace_cache__drop(c);
+
+        entry->key = key;
+        hlist_add_head(&entry->hash, &c->hashtable[hash_32(key, c->bits)]);
+
+        return 0;
+}
+
+void *auxtrace_cache__lookup(struct auxtrace_cache *c, u32 key)
+{
+        struct auxtrace_cache_entry *entry;
+        struct hlist_head *hlist;
+
+        if (!c)
+                return NULL;
+
+        hlist = &c->hashtable[hash_32(key, c->bits)];
+        hlist_for_each_entry(entry, hlist, hash) {
+                if (entry->key == key)
+                        return entry;
+        }
+
+        return NULL;
+}
diff --git a/tools/perf/util/auxtrace.h b/tools/perf/util/auxtrace.h
index ba78d825bf73..53b60a64a693 100644
--- a/tools/perf/util/auxtrace.h
+++ b/tools/perf/util/auxtrace.h
@@ -333,6 +333,20 @@ int auxtrace_heap__add(struct auxtrace_heap *heap, unsigned int queue_nr,
 void auxtrace_heap__pop(struct auxtrace_heap *heap);
 void auxtrace_heap__free(struct auxtrace_heap *heap);
 
+struct auxtrace_cache_entry {
+        struct hlist_node hash;
+        u32 key;
+};
+
+struct auxtrace_cache *auxtrace_cache__new(unsigned int bits, size_t entry_size,
+                                           unsigned int limit_percent);
+void auxtrace_cache__free(struct auxtrace_cache *auxtrace_cache);
+void *auxtrace_cache__alloc_entry(struct auxtrace_cache *c);
+void auxtrace_cache__free_entry(struct auxtrace_cache *c, void *entry);
+int auxtrace_cache__add(struct auxtrace_cache *c, u32 key,
+                        struct auxtrace_cache_entry *entry);
+void *auxtrace_cache__lookup(struct auxtrace_cache *c, u32 key);
+
 struct auxtrace_record *auxtrace_record__init(struct perf_evlist *evlist,
                                               int *err);