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[Qemu-devel] [PATCH v4 2/4 for-3.0] qcow2: Options' documentation fixes
From: |
Leonid Bloch |
Subject: |
[Qemu-devel] [PATCH v4 2/4 for-3.0] qcow2: Options' documentation fixes |
Date: |
Wed, 25 Jul 2018 01:17:48 +0300 |
Signed-off-by: Leonid Bloch <address@hidden>
---
docs/qcow2-cache.txt | 3 +++
qemu-options.hx | 10 ++++++----
2 files changed, 9 insertions(+), 4 deletions(-)
diff --git a/docs/qcow2-cache.txt b/docs/qcow2-cache.txt
index 8a09a5cc5f..3673f2be0e 100644
--- a/docs/qcow2-cache.txt
+++ b/docs/qcow2-cache.txt
@@ -130,6 +130,9 @@ 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.
+- At most two of "l2-cache-size", "refcount-cache-size", and "cache-size"
+ can be set simultaneously.
+
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
diff --git a/qemu-options.hx b/qemu-options.hx
index b1bf0f485f..13ece21cb6 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -752,15 +752,17 @@ image file)
@item cache-size
The maximum total size of the L2 table and refcount block caches in bytes
-(default: 1048576 bytes or 8 clusters, whichever is larger)
@item l2-cache-size
-The maximum size of the L2 table cache in bytes
-(default: 4/5 of the total cache size)
+The maximum size of the L2 table cache.
+(default: if cache-size is not defined - 1048576 bytes or 8 clusters, whichever
+is larger; otherwise, as large as possible or needed within the cache-size,
+while permitting the requested or the minimal refcount cache size)
@item refcount-cache-size
The maximum size of the refcount block cache in bytes
-(default: 1/5 of the total cache size)
+(default: 4 times the cluster size, or any portion of the cache-size, if it is
+specified and large enough, left over after allocating the full L2 cache)
@item cache-clean-interval
Clean unused entries in the L2 and refcount caches. The interval is in seconds.
--
2.14.1