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Re: [Qemu-block] [PATCH v12 8/9] qcow2: Set the default cache-clean-inte
From: |
Eric Blake |
Subject: |
Re: [Qemu-block] [PATCH v12 8/9] qcow2: Set the default cache-clean-interval to 10 minutes |
Date: |
Thu, 27 Sep 2018 10:53:34 -0500 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.0 |
On 9/26/18 11:04 AM, Leonid Bloch wrote:
The default cache-clean-interval is set to 10 minutes, in order to lower
the overhead of the qcow2 caches (before the default was 0, i.e.
disabled).
* For non-Linux platforms the default is kept at 0, because
cache-clean-interval is not supported there yet.
Signed-off-by: Leonid Bloch <address@hidden>
Reviewed-by: Alberto Garcia <address@hidden>
Reviewed-by: Kevin Wolf <address@hidden>
---
@@ -76,13 +76,15 @@
#ifdef CONFIG_LINUX
#define DEFAULT_L2_CACHE_MAX_SIZE S_32MiB
+#define DEFAULT_CACHE_CLEAN_INTERVAL 600 /* seconds */
#else
#define DEFAULT_L2_CACHE_MAX_SIZE S_8MiB
+/* Cache clean interval is currently available only on Linux, so must be 0 */
+#define DEFAULT_CACHE_CLEAN_INTERVAL 0
#endif
+++ b/docs/qcow2-cache.txt
@@ -210,8 +210,8 @@ This example removes all unused cache entries every 15
minutes:
-drive file=hd.qcow2,cache-clean-interval=900
-If unset, the default value for this parameter is 0 and it disables
-this feature.
+If unset, the default value for this parameter is 600. Setting it to 0
+disables this feature.
Should this wording mention that the non-zero default is only on Linux
(or rather, only on platforms where a non-zero value makes a difference)?
Note that this functionality currently relies on the MADV_DONTNEED
argument for madvise() to actually free the memory. This is a
diff --git a/qapi/block-core.json b/qapi/block-core.json
index ac3b48ee54..46dac23d2f 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -2895,7 +2895,8 @@
#
# @cache-clean-interval: clean unused entries in the L2 and refcount
# caches. The interval is in seconds. The default
value
-# is 0 and it disables this feature (since 2.5)
+# is 600, and 0 disables this feature. (since 2.5)
and again here
+#
# @encrypt: Image decryption options. Mandatory for
# encrypted images, except when doing a metadata-only
# probe of the image. (since 2.10)
diff --git a/qemu-options.hx b/qemu-options.hx
index 14aee78c6c..52d9d9f06d 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -747,7 +747,7 @@ it which is not used for the L2 cache)
@item cache-clean-interval
Clean unused entries in the L2 and refcount caches. The interval is in
seconds.
-The default value is 0 and it disables this feature.
+The default value is 600. Setting it to 0 disables this feature.
and here?
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
- [Qemu-block] [PATCH v12 0/9] Take the image size into account when allocating the L2 cache, Leonid Bloch, 2018/09/26
- [Qemu-block] [PATCH v12 2/9] include: Add a lookup table of sizes, Leonid Bloch, 2018/09/26
- [Qemu-block] [PATCH v12 1/9] qcow2: Options' documentation fixes, Leonid Bloch, 2018/09/26
- [Qemu-block] [PATCH v12 4/9] qcow2: Avoid duplication in setting the refcount cache size, Leonid Bloch, 2018/09/26
- [Qemu-block] [PATCH v12 5/9] qcow2: Assign the L2 cache relatively to the image size, Leonid Bloch, 2018/09/26
- [Qemu-block] [PATCH v12 7/9] qcow2: Resize the cache upon image resizing, Leonid Bloch, 2018/09/26
- [Qemu-block] [PATCH v12 6/9] qcow2: Increase the default upper limit on the L2 cache size, Leonid Bloch, 2018/09/26
- [Qemu-block] [PATCH v12 3/9] qcow2: Make sizes more humanly readable, Leonid Bloch, 2018/09/26
- [Qemu-block] [PATCH v12 8/9] qcow2: Set the default cache-clean-interval to 10 minutes, Leonid Bloch, 2018/09/26
- [Qemu-block] [PATCH v12 9/9] qcow2: Explicit number replaced by a constant, Leonid Bloch, 2018/09/26
- Re: [Qemu-block] [PATCH v12 0/9] Take the image size into account when allocating the L2 cache, Kevin Wolf, 2018/09/27