On 27.05.2015 11:46, Alberto Garcia wrote:
This adds a new 'cache-clean-interval' option that cleans all qcow2
cache entries that haven't been used in a certain interval, given in
This allows setting a large L2 cache size so it can handle scenarios
with lots of I/O and at the same time use little memory during periods
This feature currently relies on MADV_DONTNEED to free that memory, so
it is not useful in systems that don't follow that behavior.
@@ -41,6 +41,10 @@
# @corrupt: #optional true if the image has been marked corrupt;
only valid for
# compat >= 1.1 (since 2.2)
+# @cache-clean-interval: interval in seconds after which unused L2 and
+# refcount cache entries are removed. If 0 then
+# this feature is not enabled (since 2.4)
# @refcount-bits: width of a refcount entry in bits (since 2.3)
# Since: 1.7
@@ -50,7 +54,8 @@
- 'refcount-bits': 'int'
+ 'refcount-bits': 'int',
+ 'cache-clean-interval': 'int'
I'm not too happy about making this part of ImageInfoSpecificQCow2. Two
reasons for this: First, it's eventually part of ImageInfo, which is
defined as "Information about a QEMU image file", but this option cannot
be set in the image file itself but is only a run-time option.
Second, my original goal for ImageInfoSpecific was to provide more
information through qemu-img info, and this value will look pretty
I don't know how to resolve this quandary, though. Since qemu cannot
change this interval by itself, I think not providing an interface for
reading it is fine. On the other hand, if Eric finds such an interface
absolutely mandatory, I can't think of a better place to return it than