On 07/24/2018 06:21 PM, Eric Blake wrote:
On 07/24/2018 07:17 AM, Leonid Bloch wrote:
Signed-off-by: Leonid Bloch [1]<[email protected]>
---
docs/qcow2-cache.txt | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/docs/qcow2-cache.txt b/docs/qcow2-cache.txt
index a0a1267482..43c0faaddb 100644
--- a/docs/qcow2-cache.txt
+++ b/docs/qcow2-cache.txt
@@ -110,11 +110,12 @@ How to configure the cache sizes
Cache sizes can be configured using the -drive option in the
command-line, or the 'blockdev-add' QMP command.
-There are three options available, and all of them take bytes:
+There are four options available:
-"l2-cache-size": maximum size of the L2 table cache
-"refcount-cache-size": maximum size of the refcount block cache
-"cache-size": maximum size of both caches combined
+"l2-cache-size": maximum size of the L2 table cache (bytes,
K, M)
+"refcount-cache-size": maximum size of the refcount block cache
(bytes, K, M)
+"cache-size": maximum size of both caches combined
(bytes, K, M)
+"l2-cache-full": make the L2 cache cover the full image
(boolean)
There are a few things that need to be taken into account:
Worth mentioning that the first three can be combined (although
usually you'll never specify more than 2; as specifying all 3
requires that you perform the correct addition), but that the third
is mutually exclusive?
Actually, only 2 of the first 3 can be specified. But you're right, I
need to write about mutual exclusivity in the docs. Will fix in v2.
Thanks!
@@ -130,6 +131,9 @@ There are a few things that need to be taken
into account:
memory as possible to the L2 cache before increasing the
refcount
cache size.
+- If "l2-cache-full" is specified, QEMU will assign enough memory
+ to the L2 cache to cover the entire size of the image.
+
Unlike L2 tables, refcount blocks are not used during normal I/O
but
only during allocations and internal snapshots. In most cases they
are
accessed sequentially (even during random guest I/O) so increasing
the
References
1. mailto:[email protected]
