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[Qemu-devel] [PATCH 02/31] qcow2: Add table size field to Qcow2Cache
From: |
Alberto Garcia |
Subject: |
[Qemu-devel] [PATCH 02/31] qcow2: Add table size field to Qcow2Cache |
Date: |
Thu, 12 Oct 2017 16:05:16 +0300 |
The table size in the qcow2 cache is currently equal to the cluster
size. This doesn't allow us to use the cache memory efficiently,
particularly with large cluster sizes, so we need to be able to have
smaller cache tables that are independent from the cluster size. This
patch adds a new field to Qcow2Cache that we can use instead of the
cluster size.
The current table size is still being initialized to the cluster size,
so there are no semantic changes yet, but this patch will allow us to
prepare the rest of the code and simplify a few function calls.
Signed-off-by: Alberto Garcia <address@hidden>
---
block/qcow2-cache.c | 27 +++++++++++++--------------
1 file changed, 13 insertions(+), 14 deletions(-)
diff --git a/block/qcow2-cache.c b/block/qcow2-cache.c
index 75746a7f43..72cb7148ff 100644
--- a/block/qcow2-cache.c
+++ b/block/qcow2-cache.c
@@ -39,6 +39,7 @@ struct Qcow2Cache {
Qcow2CachedTable *entries;
struct Qcow2Cache *depends;
int size;
+ int table_size;
bool depends_on_flush;
void *table_array;
uint64_t lru_counter;
@@ -48,17 +49,15 @@ struct Qcow2Cache {
static inline void *qcow2_cache_get_table_addr(BlockDriverState *bs,
Qcow2Cache *c, int table)
{
- BDRVQcow2State *s = bs->opaque;
- return (uint8_t *) c->table_array + (size_t) table * s->cluster_size;
+ return (uint8_t *) c->table_array + (size_t) table * c->table_size;
}
static inline int qcow2_cache_get_table_idx(BlockDriverState *bs,
Qcow2Cache *c, void *table)
{
- BDRVQcow2State *s = bs->opaque;
ptrdiff_t table_offset = (uint8_t *) table - (uint8_t *) c->table_array;
- int idx = table_offset / s->cluster_size;
- assert(idx >= 0 && idx < c->size && table_offset % s->cluster_size == 0);
+ int idx = table_offset / c->table_size;
+ assert(idx >= 0 && idx < c->size && table_offset % c->table_size == 0);
return idx;
}
@@ -67,10 +66,9 @@ static void qcow2_cache_table_release(BlockDriverState *bs,
Qcow2Cache *c,
{
/* Using MADV_DONTNEED to discard memory is a Linux-specific feature */
#ifdef CONFIG_LINUX
- BDRVQcow2State *s = bs->opaque;
void *t = qcow2_cache_get_table_addr(bs, c, i);
int align = getpagesize();
- size_t mem_size = (size_t) s->cluster_size * num_tables;
+ size_t mem_size = (size_t) c->table_size * num_tables;
size_t offset = QEMU_ALIGN_UP((uintptr_t) t, align) - (uintptr_t) t;
size_t length = QEMU_ALIGN_DOWN(mem_size - offset, align);
if (length > 0) {
@@ -120,9 +118,10 @@ Qcow2Cache *qcow2_cache_create(BlockDriverState *bs, int
num_tables)
c = g_new0(Qcow2Cache, 1);
c->size = num_tables;
+ c->table_size = s->cluster_size;
c->entries = g_try_new0(Qcow2CachedTable, num_tables);
c->table_array = qemu_try_blockalign(bs->file->bs,
- (size_t) num_tables *
s->cluster_size);
+ (size_t) num_tables * c->table_size);
if (!c->entries || !c->table_array) {
qemu_vfree(c->table_array);
@@ -191,13 +190,13 @@ static int qcow2_cache_entry_flush(BlockDriverState *bs,
Qcow2Cache *c, int i)
if (c == s->refcount_block_cache) {
ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_REFCOUNT_BLOCK,
- c->entries[i].offset, s->cluster_size);
+ c->entries[i].offset, c->table_size);
} else if (c == s->l2_table_cache) {
ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_ACTIVE_L2,
- c->entries[i].offset, s->cluster_size);
+ c->entries[i].offset, c->table_size);
} else {
ret = qcow2_pre_write_overlap_check(bs, 0,
- c->entries[i].offset, s->cluster_size);
+ c->entries[i].offset, c->table_size);
}
if (ret < 0) {
@@ -211,7 +210,7 @@ static int qcow2_cache_entry_flush(BlockDriverState *bs,
Qcow2Cache *c, int i)
}
ret = bdrv_pwrite(bs->file, c->entries[i].offset,
- qcow2_cache_get_table_addr(bs, c, i), s->cluster_size);
+ qcow2_cache_get_table_addr(bs, c, i), c->table_size);
if (ret < 0) {
return ret;
}
@@ -318,7 +317,7 @@ static int qcow2_cache_do_get(BlockDriverState *bs,
Qcow2Cache *c,
offset, read_from_disk);
/* Check if the table is already cached */
- i = lookup_index = (offset / s->cluster_size * 4) % c->size;
+ i = lookup_index = (offset / c->table_size * 4) % c->size;
do {
const Qcow2CachedTable *t = &c->entries[i];
if (t->offset == offset) {
@@ -359,7 +358,7 @@ static int qcow2_cache_do_get(BlockDriverState *bs,
Qcow2Cache *c,
ret = bdrv_pread(bs->file, offset,
qcow2_cache_get_table_addr(bs, c, i),
- s->cluster_size);
+ c->table_size);
if (ret < 0) {
return ret;
}
--
2.11.0
- [Qemu-devel] [PATCH 00/31] Allow configuring the qcow2 L2 cache entry size, Alberto Garcia, 2017/10/12
- [Qemu-devel] [PATCH 28/31] qcow2: Rename l2_table in count_contiguous_clusters(), Alberto Garcia, 2017/10/12
- [Qemu-devel] [PATCH 02/31] qcow2: Add table size field to Qcow2Cache,
Alberto Garcia <=
- [Qemu-devel] [PATCH 31/31] qcow2: Allow configuring the L2 slice size, Alberto Garcia, 2017/10/12
- [Qemu-devel] [PATCH 27/31] qcow2: Rename l2_table in qcow2_alloc_compressed_cluster_offset(), Alberto Garcia, 2017/10/12
- [Qemu-devel] [PATCH 30/31] qcow2: Rename l2_table in count_cow_clusters(), Alberto Garcia, 2017/10/12
- [Qemu-devel] [PATCH 26/31] qcow2: Update qcow2_truncate() to support L2 slices, Alberto Garcia, 2017/10/12
- [Qemu-devel] [PATCH 29/31] qcow2: Rename l2_table in count_contiguous_clusters_unallocated(), Alberto Garcia, 2017/10/12
- [Qemu-devel] [PATCH 25/31] qcow2: Update expand_zero_clusters_in_l1() to support L2 slices, Alberto Garcia, 2017/10/12
- [Qemu-devel] [PATCH 24/31] qcow2: Update qcow2_update_snapshot_refcount() to support L2 slices, Alberto Garcia, 2017/10/12
- [Qemu-devel] [PATCH 23/31] qcow2: Update zero_single_l2() to support L2 slices, Alberto Garcia, 2017/10/12
- [Qemu-devel] [PATCH 22/31] qcow2: Update discard_single_l2() to support L2 slices, Alberto Garcia, 2017/10/12
- [Qemu-devel] [PATCH 21/31] qcow2: Update handle_alloc() to support L2 slices, Alberto Garcia, 2017/10/12