On 2021/08/23 10:35, Shinichiro Kawasaki wrote:
[...]
>>> diff --git a/thread_options.h b/thread_options.h
>>> index 4b4ecfe1..6fe1cad7 100644
>>> --- a/thread_options.h
>>> +++ b/thread_options.h
>>> @@ -189,6 +189,7 @@ struct thread_options {
>>> unsigned int thinktime_spin;
>>> unsigned int thinktime_blocks;
>>> unsigned int thinktime_blocks_type;
>>> + unsigned int thinktime_iotime;
>>> unsigned int fsync_blocks;
>>> unsigned int fdatasync_blocks;
>>> unsigned int barrier_blocks;
>>> @@ -500,6 +501,8 @@ struct thread_options_pack {
>>> uint32_t thinktime_spin;
>>> uint32_t thinktime_blocks;
>>> uint32_t thinktime_blocks_type;
>>> + uint32_t thinktime_iotime;
>>> + uint32_t pad6;
>>
>> Why is this needed ? Some alignement warning ?
>
> Yes. Without the pad, I observe build errors as follows:
>
> In file included from fio.h:17,
> from libfio.c:31:
> libfio.c: In function ‘initialize_fio’:
> compiler/compiler.h:31:44: error: static assertion failed: "percentile_list"
> 31 | #define compiletime_assert(condition, msg) _Static_assert(condition, msg)
> | ^~~~~~~~~~~~~~
> libfio.c:372:9: note: in expansion of macro ‘compiletime_assert’
> 372 | compiletime_assert((offsetof(struct thread_options_pack, percentile_list) % 8) == 0, "percentile_list");
> | ^~~~~~~~~~~~~~~~~~
> compiler/compiler.h:31:44: error: static assertion failed: "latency_percentile"
> 31 | #define compiletime_assert(condition, msg) _Static_assert(condition, msg)
> | ^~~~~~~~~~~~~~
> libfio.c:373:9: note: in expansion of macro ‘compiletime_assert’
> 373 | compiletime_assert((offsetof(struct thread_options_pack, latency_percentile) % 8) == 0, "latency_percentile");
> | ^~~~~~~~~~~~~~~~~~
> make: *** [Makefile:496: libfio.o] Error 1
> make: *** Waiting for unfinished jobs....
>
>> If yes, have you tried moving
>> this declaration in the struct ?
>
> Yes. I moved the new field thinktime_iotime to the end of struct
> thread_options_pack then the errors were avoided. But I wanted
> to place the new field at the same place as other thinktime related
> fields. For that purpose, I needed to add the padding pad6. I tried to
> utilize other pads such as pad2 or pad5, but it didn't work.
>
> To place the related fields at same place with padding, or to place the new
> field at different place without padding, which way to go?
I think that is a question for Jens...
Jens,
Which way do you prefer ?
--
Damien Le Moal
Western Digital Research
