[v10,8/9] qcow2: Set the default cache-clean-interval to 10 minutes

Commit Message

Leonid Bloch Sept. 21, 2018, 5:23 p.m. UTC

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 <[e-mail]>
---
 block/qcow2.c        | 2 +-
 block/qcow2.h        | 4 +++-
 docs/qcow2-cache.txt | 4 ++--
 qapi/block-core.json | 3 ++-
 qemu-options.hx      | 2 +-
 5 files changed, 9 insertions(+), 6 deletions(-)

Comments

Alberto Garcia Sept. 24, 2018, 1:40 p.m. UTC | #1

On Fri 21 Sep 2018 07:23:09 PM CEST, 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 <[e-mail]>

Reviewed-by: Alberto Garcia <[e-mail]>

Berto

Patch

diff --git a/block/qcow2.c b/block/qcow2.c
index 1445cd5360..f885afa0ed 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -944,7 +944,7 @@  static int qcow2_update_options_prepare(BlockDriverState *bs,
     /* New interval for cache cleanup timer */
     r->cache_clean_interval =
         qemu_opt_get_number(opts, QCOW2_OPT_CACHE_CLEAN_INTERVAL,
-                            s->cache_clean_interval);
+                            DEFAULT_CACHE_CLEAN_INTERVAL);
 #ifndef CONFIG_LINUX
     if (r->cache_clean_interval != 0) {
         error_setg(errp, QCOW2_OPT_CACHE_CLEAN_INTERVAL
diff --git a/block/qcow2.h b/block/qcow2.h
index 0f0e3534bf..ba430316b9 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -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
 
 #define DEFAULT_CLUSTER_SIZE S_64KiB
 
-
 #define QCOW2_OPT_LAZY_REFCOUNTS "lazy-refcounts"
 #define QCOW2_OPT_DISCARD_REQUEST "pass-discard-request"
 #define QCOW2_OPT_DISCARD_SNAPSHOT "pass-discard-snapshot"
diff --git a/docs/qcow2-cache.txt b/docs/qcow2-cache.txt
index 5965d3d094..15ae797931 100644
--- a/docs/qcow2-cache.txt
+++ b/docs/qcow2-cache.txt
@@ -209,8 +209,8 @@  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.
 
 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 4c7a37afdc..08c27b9af7 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -2827,7 +2827,8 @@ 
 #
 # @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)
+#
 # @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 d5f4bcadd4..2975fdf9f8 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -757,7 +757,7 @@  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.
 
 @item pass-discard-request
 Whether discard requests to the qcow2 device should be forwarded to the data