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-rw-r--r--block/qcow2-cache.c35
-rw-r--r--block/qcow2.c64
-rw-r--r--block/qcow2.h4
-rw-r--r--qapi/block-core.json7
4 files changed, 109 insertions, 1 deletions
diff --git a/block/qcow2-cache.c b/block/qcow2-cache.c
index f63e7d8e70..8457458418 100644
--- a/block/qcow2-cache.c
+++ b/block/qcow2-cache.c
@@ -49,6 +49,7 @@ struct Qcow2Cache {
bool depends_on_flush;
void *table_array;
uint64_t lru_counter;
+ uint64_t cache_clean_lru_counter;
};
static inline void *qcow2_cache_get_table_addr(BlockDriverState *bs,
@@ -84,6 +85,40 @@ static void qcow2_cache_table_release(BlockDriverState *bs, Qcow2Cache *c,
#endif
}
+static inline bool can_clean_entry(Qcow2Cache *c, int i)
+{
+ Qcow2CachedTable *t = &c->entries[i];
+ return t->ref == 0 && !t->dirty && t->offset != 0 &&
+ t->lru_counter <= c->cache_clean_lru_counter;
+}
+
+void qcow2_cache_clean_unused(BlockDriverState *bs, Qcow2Cache *c)
+{
+ int i = 0;
+ while (i < c->size) {
+ int to_clean = 0;
+
+ /* Skip the entries that we don't need to clean */
+ while (i < c->size && !can_clean_entry(c, i)) {
+ i++;
+ }
+
+ /* And count how many we can clean in a row */
+ while (i < c->size && can_clean_entry(c, i)) {
+ c->entries[i].offset = 0;
+ c->entries[i].lru_counter = 0;
+ i++;
+ to_clean++;
+ }
+
+ if (to_clean > 0) {
+ qcow2_cache_table_release(bs, c, i - to_clean, to_clean);
+ }
+ }
+
+ c->cache_clean_lru_counter = c->lru_counter;
+}
+
Qcow2Cache *qcow2_cache_create(BlockDriverState *bs, int num_tables)
{
BDRVQcowState *s = bs->opaque;
diff --git a/block/qcow2.c b/block/qcow2.c
index 76c331b387..ea34ae2da5 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -467,6 +467,11 @@ static QemuOptsList qcow2_runtime_opts = {
.type = QEMU_OPT_SIZE,
.help = "Maximum refcount block cache size",
},
+ {
+ .name = QCOW2_OPT_CACHE_CLEAN_INTERVAL,
+ .type = QEMU_OPT_NUMBER,
+ .help = "Clean unused cache entries after this time (in seconds)",
+ },
{ /* end of list */ }
},
};
@@ -482,6 +487,49 @@ static const char *overlap_bool_option_names[QCOW2_OL_MAX_BITNR] = {
[QCOW2_OL_INACTIVE_L2_BITNR] = QCOW2_OPT_OVERLAP_INACTIVE_L2,
};
+static void cache_clean_timer_cb(void *opaque)
+{
+ BlockDriverState *bs = opaque;
+ BDRVQcowState *s = bs->opaque;
+ qcow2_cache_clean_unused(bs, s->l2_table_cache);
+ qcow2_cache_clean_unused(bs, s->refcount_block_cache);
+ timer_mod(s->cache_clean_timer, qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) +
+ (int64_t) s->cache_clean_interval * 1000);
+}
+
+static void cache_clean_timer_init(BlockDriverState *bs, AioContext *context)
+{
+ BDRVQcowState *s = bs->opaque;
+ if (s->cache_clean_interval > 0) {
+ s->cache_clean_timer = aio_timer_new(context, QEMU_CLOCK_VIRTUAL,
+ SCALE_MS, cache_clean_timer_cb,
+ bs);
+ timer_mod(s->cache_clean_timer, qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) +
+ (int64_t) s->cache_clean_interval * 1000);
+ }
+}
+
+static void cache_clean_timer_del(BlockDriverState *bs)
+{
+ BDRVQcowState *s = bs->opaque;
+ if (s->cache_clean_timer) {
+ timer_del(s->cache_clean_timer);
+ timer_free(s->cache_clean_timer);
+ s->cache_clean_timer = NULL;
+ }
+}
+
+static void qcow2_detach_aio_context(BlockDriverState *bs)
+{
+ cache_clean_timer_del(bs);
+}
+
+static void qcow2_attach_aio_context(BlockDriverState *bs,
+ AioContext *new_context)
+{
+ cache_clean_timer_init(bs, new_context);
+}
+
static void read_cache_sizes(BlockDriverState *bs, QemuOpts *opts,
uint64_t *l2_cache_size,
uint64_t *refcount_cache_size, Error **errp)
@@ -555,6 +603,7 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags,
const char *opt_overlap_check, *opt_overlap_check_template;
int overlap_check_template = 0;
uint64_t l2_cache_size, refcount_cache_size;
+ uint64_t cache_clean_interval;
ret = bdrv_pread(bs->file, 0, &header, sizeof(header));
if (ret < 0) {
@@ -848,6 +897,16 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags,
goto fail;
}
+ cache_clean_interval =
+ qemu_opt_get_number(opts, QCOW2_OPT_CACHE_CLEAN_INTERVAL, 0);
+ if (cache_clean_interval > UINT_MAX) {
+ error_setg(errp, "Cache clean interval too big");
+ ret = -EINVAL;
+ goto fail;
+ }
+ s->cache_clean_interval = cache_clean_interval;
+ cache_clean_timer_init(bs, bdrv_get_aio_context(bs));
+
s->cluster_cache = g_malloc(s->cluster_size);
/* one more sector for decompressed data alignment */
s->cluster_data = qemu_try_blockalign(bs->file, QCOW_MAX_CRYPT_CLUSTERS
@@ -1013,6 +1072,7 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags,
qemu_vfree(s->l1_table);
/* else pre-write overlap checks in cache_destroy may crash */
s->l1_table = NULL;
+ cache_clean_timer_del(bs);
if (s->l2_table_cache) {
qcow2_cache_destroy(bs, s->l2_table_cache);
}
@@ -1471,6 +1531,7 @@ static void qcow2_close(BlockDriverState *bs)
}
}
+ cache_clean_timer_del(bs);
qcow2_cache_destroy(bs, s->l2_table_cache);
qcow2_cache_destroy(bs, s->refcount_block_cache);
@@ -2977,6 +3038,9 @@ BlockDriver bdrv_qcow2 = {
.create_opts = &qcow2_create_opts,
.bdrv_check = qcow2_check,
.bdrv_amend_options = qcow2_amend_options,
+
+ .bdrv_detach_aio_context = qcow2_detach_aio_context,
+ .bdrv_attach_aio_context = qcow2_attach_aio_context,
};
static void bdrv_qcow2_init(void)
diff --git a/block/qcow2.h b/block/qcow2.h
index 72e132838a..71dafd6dc9 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -96,6 +96,7 @@
#define QCOW2_OPT_CACHE_SIZE "cache-size"
#define QCOW2_OPT_L2_CACHE_SIZE "l2-cache-size"
#define QCOW2_OPT_REFCOUNT_CACHE_SIZE "refcount-cache-size"
+#define QCOW2_OPT_CACHE_CLEAN_INTERVAL "cache-clean-interval"
typedef struct QCowHeader {
uint32_t magic;
@@ -239,6 +240,8 @@ typedef struct BDRVQcowState {
Qcow2Cache* l2_table_cache;
Qcow2Cache* refcount_block_cache;
+ QEMUTimer *cache_clean_timer;
+ unsigned cache_clean_interval;
uint8_t *cluster_cache;
uint8_t *cluster_data;
@@ -581,6 +584,7 @@ int qcow2_cache_set_dependency(BlockDriverState *bs, Qcow2Cache *c,
Qcow2Cache *dependency);
void qcow2_cache_depends_on_flush(Qcow2Cache *c);
+void qcow2_cache_clean_unused(BlockDriverState *bs, Qcow2Cache *c);
int qcow2_cache_empty(BlockDriverState *bs, Qcow2Cache *c);
int qcow2_cache_get(BlockDriverState *bs, Qcow2Cache *c, uint64_t offset,
diff --git a/qapi/block-core.json b/qapi/block-core.json
index 7b2efb8678..bb2189ef3a 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -1592,6 +1592,10 @@
# @refcount-cache-size: #optional the maximum size of the refcount block cache
# in bytes (since 2.2)
#
+# @cache-clean-interval: #optional clean unused entries in the L2 and refcount
+# caches. The interval is in seconds. The default value
+# is 0 and it disables this feature (since 2.5)
+#
# Since: 1.7
##
{ 'struct': 'BlockdevOptionsQcow2',
@@ -1603,7 +1607,8 @@
'*overlap-check': 'Qcow2OverlapChecks',
'*cache-size': 'int',
'*l2-cache-size': 'int',
- '*refcount-cache-size': 'int' } }
+ '*refcount-cache-size': 'int',
+ '*cache-clean-interval': 'int' } }
##
generated by cgit v1.2.3 (git 2.26.2) at 2024-12-04 23:40:34 +0000