From: Max Reitz <mreitz@redhat.com>
To: qemu-block@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>, Max Reitz <mreitz@redhat.com>,
Alberto Garcia <berto@igalia.com>,
qemu-devel@nongnu.org, Alexander Graf <agraf@suse.de>
Subject: [Qemu-devel] [PATCH 1/3] qcow2: Set MIN_L2_CACHE_SIZE to 2
Date: Mon, 1 Jun 2015 18:09:17 +0200 [thread overview]
Message-ID: <1433174959-7176-2-git-send-email-mreitz@redhat.com> (raw)
In-Reply-To: <1433174959-7176-1-git-send-email-mreitz@redhat.com>
The L2 cache must cover at least two L2 tables, because during COW two
L2 tables are accessed simultaneously.
Reported-by: Alexander Graf <agraf@suse.de>
Cc: qemu-stable <qemu-stable@nongnu.org>
Signed-off-by: Max Reitz <mreitz@redhat.com>
---
block/qcow2.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/block/qcow2.h b/block/qcow2.h
index 0076512..aa20022 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -62,7 +62,8 @@
#define MIN_CLUSTER_BITS 9
#define MAX_CLUSTER_BITS 21
-#define MIN_L2_CACHE_SIZE 1 /* cluster */
+/* Must be at least 2 to cover COW */
+#define MIN_L2_CACHE_SIZE 2 /* clusters */
/* Must be at least 4 to cover all cases of refcount table growth */
#define MIN_REFCOUNT_CACHE_SIZE 4 /* clusters */
--
2.4.1
next prev parent reply other threads:[~2015-06-01 16:09 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-01 16:09 [Qemu-devel] [PATCH 0/3] qcow2: Fix MIN_L2_CACHE_SIZE Max Reitz
2015-06-01 16:09 ` Max Reitz [this message]
2015-06-01 16:10 ` [Qemu-devel] [PATCH 1/3] qcow2: Set MIN_L2_CACHE_SIZE to 2 Max Reitz
2015-06-01 16:12 ` Alexander Graf
2015-06-01 16:14 ` Alberto Garcia
2015-06-01 16:09 ` [Qemu-devel] [PATCH 2/3] iotests: qcow2 COW with minimal L2 cache size Max Reitz
2015-06-01 17:01 ` Alberto Garcia
2015-06-01 16:09 ` [Qemu-devel] [PATCH 3/3] qcow2: Add DEFAULT_L2_CACHE_CLUSTERS Max Reitz
2015-06-01 17:16 ` Alberto Garcia
2015-06-02 9:31 ` [Qemu-devel] [PATCH 0/3] qcow2: Fix MIN_L2_CACHE_SIZE Kevin Wolf
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