From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47659) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XKqCN-0000yE-SK for qemu-devel@nongnu.org; Fri, 22 Aug 2014 10:52:23 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XKqCH-0005cY-Ch for qemu-devel@nongnu.org; Fri, 22 Aug 2014 10:52:15 -0400 Received: from mx1.redhat.com ([209.132.183.28]:9599) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XKqCH-0005cO-4A for qemu-devel@nongnu.org; Fri, 22 Aug 2014 10:52:09 -0400 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s7MEq8dM027506 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Fri, 22 Aug 2014 10:52:08 -0400 From: Kevin Wolf Date: Fri, 22 Aug 2014 16:51:31 +0200 Message-Id: <1408719113-5316-8-git-send-email-kwolf@redhat.com> In-Reply-To: <1408719113-5316-1-git-send-email-kwolf@redhat.com> References: <1408719113-5316-1-git-send-email-kwolf@redhat.com> Subject: [Qemu-devel] [PULL 07/29] qcow2: Constant cache size in bytes List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: kwolf@redhat.com From: Max Reitz Specifying the metadata cache sizes in clusters results in less clusters (and much less bytes) covered for small cluster sizes and vice versa. Using a constant byte size reduces this difference, and makes it possible to manually specify the cache size in an easily comprehensible unit. Signed-off-by: Max Reitz Signed-off-by: Kevin Wolf --- block/qcow2.c | 15 +++++++++++++-- block/qcow2.h | 10 ++++++++-- 2 files changed, 21 insertions(+), 4 deletions(-) diff --git a/block/qcow2.c b/block/qcow2.c index 435e0e1..0f1be2e 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -470,6 +470,7 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags, uint64_t l1_vm_state_index; const char *opt_overlap_check; int overlap_check_template = 0; + uint64_t l2_cache_size, refcount_cache_size; ret = bdrv_pread(bs->file, 0, &header, sizeof(header)); if (ret < 0) { @@ -707,8 +708,18 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags, } /* alloc L2 table/refcount block cache */ - s->l2_table_cache = qcow2_cache_create(bs, L2_CACHE_SIZE); - s->refcount_block_cache = qcow2_cache_create(bs, REFCOUNT_CACHE_SIZE); + l2_cache_size = DEFAULT_L2_CACHE_BYTE_SIZE / s->cluster_size; + if (l2_cache_size < MIN_L2_CACHE_SIZE) { + l2_cache_size = MIN_L2_CACHE_SIZE; + } + + refcount_cache_size = l2_cache_size / DEFAULT_L2_REFCOUNT_SIZE_RATIO; + if (refcount_cache_size < MIN_REFCOUNT_CACHE_SIZE) { + refcount_cache_size = MIN_REFCOUNT_CACHE_SIZE; + } + + s->l2_table_cache = qcow2_cache_create(bs, l2_cache_size); + s->refcount_block_cache = qcow2_cache_create(bs, refcount_cache_size); if (s->l2_table_cache == NULL || s->refcount_block_cache == NULL) { error_setg(errp, "Could not allocate metadata caches"); ret = -ENOMEM; diff --git a/block/qcow2.h b/block/qcow2.h index b49424b..671783d 100644 --- a/block/qcow2.h +++ b/block/qcow2.h @@ -64,10 +64,16 @@ #define MIN_CLUSTER_BITS 9 #define MAX_CLUSTER_BITS 21 -#define L2_CACHE_SIZE 16 +#define MIN_L2_CACHE_SIZE 1 /* cluster */ /* Must be at least 4 to cover all cases of refcount table growth */ -#define REFCOUNT_CACHE_SIZE 4 +#define MIN_REFCOUNT_CACHE_SIZE 4 /* 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 + * clusters */ +#define DEFAULT_L2_REFCOUNT_SIZE_RATIO 4 #define DEFAULT_CLUSTER_SIZE 65536 -- 1.8.3.1