Merge tag 'pull-riscv-to-apply-20231107' of https://github.com/alistair23/qemu into...

[mirror_qemu.git] / block / qed-l2-cache.c

diff --git a/block/qed-l2-cache.c b/block/qed-l2-cache.c
index 02b81a2e33c2b25c6dab746861103cf8593e2908..caf2c024c2dc33d8deea248da311067ce97d4617 100644 (file)
--- a/block/qed-l2-cache.c
+++ b/block/qed-l2-cache.c
@@ -50,6 +50,8 @@
  * table will be deleted in favor of the existing cache entry.
  */
 
+#include "qemu/osdep.h"
+#include "qemu/memalign.h"
 #include "trace.h"
 #include "qed.h"
 
@@ -100,6 +102,8 @@ CachedL2Table *qed_alloc_l2_cache_entry(L2TableCache *l2_cache)
 /**
  * Decrease an entry's reference count and free if necessary when the reference
  * count drops to zero.
+ *
+ * Called with table_lock held.
  */
 void qed_unref_l2_cache_entry(CachedL2Table *entry)
 {
@@ -121,6 +125,8 @@ void qed_unref_l2_cache_entry(CachedL2Table *entry)
  *
  * For a cached entry, this function increases the reference count and returns
  * the entry.
+ *
+ * Called with table_lock held.
  */
 CachedL2Table *qed_find_l2_cache_entry(L2TableCache *l2_cache, uint64_t offset)
 {
@@ -149,6 +155,8 @@ CachedL2Table *qed_find_l2_cache_entry(L2TableCache *l2_cache, uint64_t offset)
  * N.B. This function steals a reference to the l2_table from the caller so the
  * caller must obtain a new reference by issuing a call to
  * qed_find_l2_cache_entry().
+ *
+ * Called with table_lock held.
  */
 void qed_commit_l2_cache_entry(L2TableCache *l2_cache, CachedL2Table *l2_table)
 {
@@ -161,11 +169,25 @@ void qed_commit_l2_cache_entry(L2TableCache *l2_cache, CachedL2Table *l2_table)
         return;
     }
 
+    /* Evict an unused cache entry so we have space.  If all entries are in use
+     * we can grow the cache temporarily and we try to shrink back down later.
+     */
     if (l2_cache->n_entries >= MAX_L2_CACHE_SIZE) {
-        entry = QTAILQ_FIRST(&l2_cache->entries);
-        QTAILQ_REMOVE(&l2_cache->entries, entry, node);
-        l2_cache->n_entries--;
-        qed_unref_l2_cache_entry(entry);
+        CachedL2Table *next;
+        QTAILQ_FOREACH_SAFE(entry, &l2_cache->entries, node, next) {
+            if (entry->ref > 1) {
+                continue;
+            }
+
+            QTAILQ_REMOVE(&l2_cache->entries, entry, node);
+            l2_cache->n_entries--;
+            qed_unref_l2_cache_entry(entry);
+
+            /* Stop evicting when we've shrunk back to max size */
+            if (l2_cache->n_entries < MAX_L2_CACHE_SIZE) {
+                break;
+            }
+        }
     }
 
     l2_cache->n_entries++;