Re: [PATCH 08.5/12] qemu: Create a set of macros to handle setting block iotune values

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On 09/30/2016 07:08 AM, Erik Skultety wrote:
> On 30/09/16 12:57, John Ferlan wrote:
>>
>>
>> On 09/30/2016 04:43 AM, Erik Skultety wrote:
>>> On 28/09/16 22:27, John Ferlan wrote:
>>>> Rework the code in a set of 3 macros that will use the "base" of
>>>> 'bytes' or 'iops' and build up the prefixes of 'total_', 'read_',
>>>> and 'write_' before adding the postfixes of '_sec', '_sec_max',
>>>> and '_sec_max_length' and making the param->field comparison and
>>>> adding of the field.
>>>>
>>>> Signed-off-by: John Ferlan <jferlan@xxxxxxxxxx>
>>>> ---
>>>>
>>>>  NB: Hopefully this applies - my branch is based off of the git head
>>>>      which I refreshed prior to sending the patch
>>>>
>>>>      Since I missed 2.3, I figured why not try to make the change.
>>>>
>>>>  src/qemu/qemu_driver.c | 216 +++++++++++--------------------------------------
>>>>  1 file changed, 45 insertions(+), 171 deletions(-)
>>>>
>>>> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
>>>> index 2b5b6fc..cbf9483 100644
>>>> --- a/src/qemu/qemu_driver.c
>>>> +++ b/src/qemu/qemu_driver.c
>>>> @@ -17321,6 +17321,41 @@ qemuDomainSetBlockIoTune(virDomainPtr dom,
>>>>                                  VIR_DOMAIN_TUNABLE_BLKDEV_DISK, path) < 0)
>>>>          goto endjob;
>>>>  
>>>> +#define SET_IOTUNE_FIELD(FIELD, BOOL, CONST)                                   \
>>>> +    do {                                                                       \
>>>> +        info.FIELD = params->value.ul;                                         \
>>>> +        BOOL = true;                                                           \
>>>> +        if (virTypedParamsAddULLong(&eventParams, &eventNparams,               \
>>>> +                                    &eventMaxparams,                           \
>>>> +                                    VIR_DOMAIN_TUNABLE_BLKDEV_##CONST,         \
>>>> +                                    param->value.ul) < 0)                      \
>>>> +            goto endjob;                                                       \
>>>> +    } while (0);
>>>> +
>>>
>>> While I totally support ^^this kind of macro-based code cleanup,
>>>
>>
>> Ironically it's what I started with, but still seeing:
>>
>>     if (STREQ(param->field, VIR_DOMAIN_BLOCK_IOTUNE_TOTAL_BYTES_SEC))
>>         SET_IOTUNE_FIELD(total_bytes_sec, bytes, TOTAL_BYTES_SEC);
>>     else if (STREQ(param->field,
>>                    VIR_DOMAIN_BLOCK_IOTUNE_READ_BYTES_SEC))
>>         SET_IOTUNE_FIELD(read_bytes_sec, bytes, READ_BYTES_SEC);
>>     else if (STREQ(param->field,
>>                    VIR_DOMAIN_BLOCK_IOTUNE_WRITE_BYTES_SEC))
>>         SET_IOTUNE_FIELD(write_bytes_sec, bytes, WRITE_BYTES_SEC);
>>
> 
> Yeah, I also posted some suggestion in my original reply, have a look at
> that, to make it short I think that construction like this might work as
> well and is still slightly more readable:
> 
> SET_IOTUNE_FIELD(total_bytes_sec, bytes, TOTAL_BYTES_SEC);
> SET_IOTUNE_FIELD(read_bytes_sec, bytes, READ_BYTES_SEC);
> SET_IOTUNE_FIELD(write_bytes_sec, bytes, WRITE_BYTES_SEC);
> 
> I purposely got rid of the if-else-if construction altogether because
> the compiler might actually optimize it, as I said, see my original
> reply to this patch and tell me what you think.
> 

So essentially I end up with two macros and 7 calls to those macros:

#define SET_IOTUNE(FIELD, BOOL, CONST)                                         \
    do {                                                                       \
        info.FIELD = params->value.ul;                                         \
        set_##BOOL = true;                                                     \
        if (virTypedParamsAddULLong(&eventParams, &eventNparams,               \
                                    &eventMaxparams,                           \
                                    VIR_DOMAIN_TUNABLE_BLKDEV_##CONST,         \
                                    param->value.ul) < 0)                      \
            goto endjob;                                                       \
    } while (0);

#define SET_IOTUNE_FIELD(FIELD, BOOL, CONST)                                   \
    if (STREQ(param->field, VIR_DOMAIN_BLOCK_IOTUNE_##CONST)) {                \
        SET_IOTUNE(FIELD, BOOL, CONST);                                        \
    } else if (STREQ(param->field, VIR_DOMAIN_BLOCK_IOTUNE_##CONST##_MAX)) {   \
        SET_IOTUNE(FIELD##_max, BOOL##_max, CONST##_MAX);                      \
    } else if (STREQ(param->field,                                             \
                     VIR_DOMAIN_BLOCK_IOTUNE_##CONST##_MAX_LENGTH)) {          \
        SET_IOTUNE(FIELD##_max_length, BOOL##_max_length, CONST##_MAX_LENGTH); \
    }


        SET_IOTUNE_FIELD(total_bytes_sec, bytes, TOTAL_BYTES_SEC);
        SET_IOTUNE_FIELD(read_bytes_sec, bytes, READ_BYTES_SEC);
        SET_IOTUNE_FIELD(write_bytes_sec, bytes, WRITE_BYTES_SEC);
        SET_IOTUNE_FIELD(total_iops_sec, iops, TOTAL_IOPS_SEC);
        SET_IOTUNE_FIELD(read_iops_sec, iops, READ_IOPS_SEC);
        SET_IOTUNE_FIELD(write_iops_sec, iops, WRITE_IOPS_SEC);
        if (STREQ(param->field, VIR_DOMAIN_BLOCK_IOTUNE_SIZE_IOPS_SEC))
            SET_IOTUNE(size_iops_sec, size_iops, SIZE_IOPS_SEC);

#undef SET_IOTUNE
#undef SET_IOTUNE_FIELD
 

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