[PATCH 1/4] Add public API for parallel compression method

[Jiang Jiacheng]

On 2023/2/7 23:36, Jiri Denemark wrote:
> On Fri, Jan 20, 2023 at 16:47:40 +0800, Jiang Jiacheng wrote:
>> Add description for VIR_MIGRATE_PARAM_COMPRESSION, it will
>> be reused in choosing compression method during multifd migration.
>> Add public API VIR_MIGRATE_PARAM_COMPRESSION_ZLIB_LEVEL,
>> VIR_MIGRATE_PARAM_COMPRESSION_ZSTD_LEVEL for migration APIs
>> to support set compress level during multifd migration.
>>
>> Signed-off-by: Jiang Jiacheng <jiangjiacheng at huawei.com>
>> ---
>>  include/libvirt/libvirt-domain.h | 24 +++++++++++++++++++++++-
>>  1 file changed, 23 insertions(+), 1 deletion(-)
>>
>> diff --git a/include/libvirt/libvirt-domain.h b/include/libvirt/libvirt-domain.h
>> index 5152ed4551..deac3687ed 100644
>> --- a/include/libvirt/libvirt-domain.h
>> +++ b/include/libvirt/libvirt-domain.h
>> @@ -1271,7 +1271,9 @@ typedef enum {
>>   * virDomainMigrate* params multiple field: name of the method used to
>>   * compress migration traffic. Supported compression methods: xbzrle, mt.
>>   * The parameter may be specified multiple times if more than one method
>> - * should be used.
>> + * should be used. Support compression methods for multifd migration: zlib,
>> + * zstd. When using with multifd migration, only one supported compression
>> + * method can be specified.
> 
> I don't think we should separate the new methods this way. And we use
> "parallel" instead of "multifd" migration. So how about:
> 
>     virDomainMigrate* params multiple field: name of the method used to
>     compress migration traffic. Supported compression methods: xbzrle,
>     mt, zlib, zstd. The parameter may be specified multiple times if more
>     than one method should be used. Not all combinations of compression
>     methods and migration options may be allowed. Parallel migration of
>     QEMU domains is only compatible with either zlib or zstd method.
> 

Thank you for your corrections and suggestions, and I will improve these
descriptions (and those in patch 4) to make them clearer and more
consistent with other descriptions.

Thanks, Jiangjiacheng

>>   *
>>   * Since: 1.3.4
>>   */
>> @@ -1351,6 +1353,26 @@ typedef enum {
>>   */
>>  # define VIR_MIGRATE_PARAM_PARALLEL_CONNECTIONS     "parallel.connections"
>>  
>> +/**
>> + * VIR_MIGRATE_PARAM_COMPRESSION_ZLIB_LEVEL:
>> + *
>> + * virDomainMigrate* params field: zlib compress level used during parallel
>> + * migration. As VIR_TYPED_PARAM_INT.
> 
> I don't think we need to explicitly mention parallel migration here. On
> the other hand, we should mention allowed values and their semantics.
> See how compression.mt.level is described:
> 
>     "Accepted values are in range 0-9. 0 is no compression, 1 is maximum
>     speed and 9 is maximum compression."
> 
>> + *
>> + * Since: 9.1.0
>> + */
>> +# define VIR_MIGRATE_PARAM_COMPRESSION_ZLIB_LEVEL      "compression.zlib.level"
>> +
>> +/**
>> + * VIR_MIGRATE_PARAM_COMPRESSION_ZSTD_LEVEL:
>> + *
>> + * virDomainMigrate* params field: zstd compress level used during parallel
>> + * migration. As VIR_TYPED_PARAM_INT.
> 
> The same comment as above.
> 
>> + *
>> + * Since: 9.1.0
>> + */
>> +# define VIR_MIGRATE_PARAM_COMPRESSION_ZSTD_LEVEL      "compression.zstd.level"
>> +
> 
> And I think documenting them next to the other
> VIR_MIGRATE_PARAM_COMPRESSION parameters would make more sense.
> 
>>  /**
>>   * VIR_MIGRATE_PARAM_TLS_DESTINATION:
>>   *
> 
> Jirka
>