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).

Signed-off-by: Leonid Bloch <lbloch@janustech.com>
---
 block/qcow2.c        | 2 +-
 block/qcow2.h        | 1 +
 docs/qcow2-cache.txt | 4 ++--
 qapi/block-core.json | 3 ++-
 qemu-options.hx      | 2 +-
 5 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/block/qcow2.c b/block/qcow2.c
index 3f75b6e701..15d849d1f0 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -941,7 +941,7 @@ 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 d77a31d932..587b053453 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -77,6 +77,7 @@
 
 #define DEFAULT_CLUSTER_SIZE 65536
 
+#define DEFAULT_CACHE_CLEAN_INTERVAL 600  /* seconds */
 
 #define QCOW2_OPT_LAZY_REFCOUNTS "lazy-refcounts"
 #define QCOW2_OPT_DISCARD_REQUEST "pass-discard-request"
diff --git a/docs/qcow2-cache.txt b/docs/qcow2-cache.txt
index c7625cdeb3..9926f83ada 100644
--- a/docs/qcow2-cache.txt
+++ b/docs/qcow2-cache.txt
@@ -202,8 +202,8 @@ 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 5b9084a394..7c6115096a 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -2830,7 +2830,8 @@
 #
 # @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. Setting 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 d6e15b2f06..8cebb0c77d 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -767,7 +767,7 @@ 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
-- 
2.17.1

On Thu 09 Aug 2018 12:11:37 AM 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).
>
> Signed-off-by: Leonid Bloch <lbloch@janustech.com>

> --- a/qapi/block-core.json
> +++ b/qapi/block-core.json
> @@ -2830,7 +2830,8 @@
>  #
>  # @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. Setting 0 disables this feature. (since 2.5)
> +#

It should be "Setting it to 0 ...".

With that corrected,

Reviewed-by: Alberto Garcia <berto@igalia.com>

Berto

On 8/9/18 12:33 PM, Alberto Garcia wrote:
> On Thu 09 Aug 2018 12:11:37 AM 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).
>>
>> Signed-off-by: Leonid Bloch <lbloch@janustech.com>
> 
>> --- a/qapi/block-core.json
>> +++ b/qapi/block-core.json
>> @@ -2830,7 +2830,8 @@
>>   #
>>   # @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. Setting 0 disables this feature. (since 2.5)
>> +#
> 
> It should be "Setting it to 0 ...".

How about:

"... is 600 (0 disables this feature). (since 2.5)"?

... To avoid the extra line. That's why I skipped the "it to" as well. 
Alternatively, maybe we can skip the defaults altogether in this file, 
just as with all the other qcow2 options there?

Leonid.

> 
> With that corrected,
> 
> Reviewed-by: Alberto Garcia <berto@igalia.com>
> 
> Berto
> 

On Thu 09 Aug 2018 12:52:34 PM CEST, Leonid Bloch wrote:
> On 8/9/18 12:33 PM, Alberto Garcia wrote:
>> On Thu 09 Aug 2018 12:11:37 AM 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).
>>>
>>> Signed-off-by: Leonid Bloch <lbloch@janustech.com>
>> 
>>> --- a/qapi/block-core.json
>>> +++ b/qapi/block-core.json
>>> @@ -2830,7 +2830,8 @@
>>>   #
>>>   # @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. Setting 0 disables this feature. (since 2.5)
>>> +#
>> 
>> It should be "Setting it to 0 ...".
>
> How about:
>
> "... is 600 (0 disables this feature). (since 2.5)"?

Or "The default is 600, and 0 disables this feature". It's ok either
way.

Berto