From a2cddcefc2f079206c872162c120cee7b695734e Mon Sep 17 00:00:00 2001
From: Max Reitz <mreitz@redhat.com>
Date: Wed, 17 Jun 2015 12:42:56 +0200
Subject: [PATCH 014/217] qcow2: Add DEFAULT_L2_CACHE_CLUSTERS
Message-id: <1434544976-15816-4-git-send-email-mreitz@redhat.com>
Patchwork-id: 66283
O-Subject: [RHEV-7.2 qemu-kvm-rhev PATCH 3/3] qcow2: Add DEFAULT_L2_CACHE_CLUSTERS
Bugzilla: 1226996
RH-Acked-by: Fam Zheng <famz@redhat.com>
RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
BZ: 1226996
If a relatively large cluster size is chosen, the default of 1 MB L2
cache is not really appropriate. In this case, unless overridden by the
user, the default cache size should not be determined by its size in
bytes but by the number of L2 tables (clusters) it is supposed to
contain.
Note that without this patch, MIN_L2_CACHE_SIZE will effectively take
over the same role. However, providing space for just two L2 tables is
not enough to be the default.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit bc85ef265a0118d044ff62ae217c186cb08e0866)
Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
block/qcow2.c | 11 ++++++++---
block/qcow2.h | 2 ++
2 files changed, 10 insertions(+), 3 deletions(-)
diff --git a/block/qcow2.c b/block/qcow2.c
index 316a8db..cab8450 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -483,9 +483,11 @@ static const char *overlap_bool_option_names[QCOW2_OL_MAX_BITNR] = {
[QCOW2_OL_INACTIVE_L2_BITNR] = QCOW2_OPT_OVERLAP_INACTIVE_L2,
};
-static void read_cache_sizes(QemuOpts *opts, uint64_t *l2_cache_size,
+static void read_cache_sizes(BlockDriverState *bs, QemuOpts *opts,
+ uint64_t *l2_cache_size,
uint64_t *refcount_cache_size, Error **errp)
{
+ BDRVQcowState *s = bs->opaque;
uint64_t combined_cache_size;
bool l2_cache_size_set, refcount_cache_size_set, combined_cache_size_set;
@@ -525,7 +527,9 @@ static void read_cache_sizes(QemuOpts *opts, uint64_t *l2_cache_size,
}
} else {
if (!l2_cache_size_set && !refcount_cache_size_set) {
- *l2_cache_size = DEFAULT_L2_CACHE_BYTE_SIZE;
+ *l2_cache_size = MAX(DEFAULT_L2_CACHE_BYTE_SIZE,
+ (uint64_t)DEFAULT_L2_CACHE_CLUSTERS
+ * s->cluster_size);
*refcount_cache_size = *l2_cache_size
/ DEFAULT_L2_REFCOUNT_SIZE_RATIO;
} else if (!l2_cache_size_set) {
@@ -803,7 +807,8 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags,
goto fail;
}
- read_cache_sizes(opts, &l2_cache_size, &refcount_cache_size, &local_err);
+ read_cache_sizes(bs, opts, &l2_cache_size, &refcount_cache_size,
+ &local_err);
if (local_err) {
error_propagate(errp, local_err);
ret = -EINVAL;
diff --git a/block/qcow2.h b/block/qcow2.h
index 2f20949..22f9ac2 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -68,6 +68,8 @@
/* Must be at least 4 to cover all cases of refcount table growth */
#define MIN_REFCOUNT_CACHE_SIZE 4 /* clusters */
+/* Whichever is more */
+#define DEFAULT_L2_CACHE_CLUSTERS 8 /* clusters */
#define DEFAULT_L2_CACHE_BYTE_SIZE 1048576 /* bytes */
/* The refblock cache needs only a fourth of the L2 cache size to cover as many
--
1.8.3.1