Re: [Qemu-devel] [PATCH v12 8/9] qcow2: Set the default cache-clean-interval to 10 minutes

[Leonid Bloch]

On September 27, 2018 5:53:34 PM CEST, Eric Blake <address@hidden> wrote:
>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)?

Yes, I think it should mention it, thanks. Should I send a separate patch?

Leonid.

>
>>   
>>   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?

-- 
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