Hello Davi!
* Davi Arnaut <davi.arnaut@stripped> [10/12/16 14:39]:
>>>> Also I have found the following article claiming that using gethrtime
>>>> gives boost to MySQL performance even on Solaris 10:
>>>>
>>>> http://developers.sun.com/solaris/articles/mysql_perf_tune.html
>>>
>>> I find this article highly suspicious since this hack exist at least
>>> since July of 2007. Also, obviously, the explanation there is simply
>>> wrong as we _can't_ use gethrtime for timing.
>>
>> Well, it is not very clear when this article was written.
>>
>> But it seems to be focused on MySQL 5.0 which AFAICS doesn't
>> include this particular hack. This can explain its results.
>>
>> I agree that explanation is somewhat confusing. But in the end
>> I think the suggestion in article boils down to using time()
>> implementation which is based on gethrtime() similarly to
>> hack in out code. This is achieved by linking MySQL with
>> -lfasttime library described at
>> http://developers.sun.com/solaris/articles/time_stamp.html.
>
> Similar in the sense that it has the same bug and is not thread safe --
> the MySQL one is wrapper inside a mutex.
>
> How about we ask the benchmark team to actually measure this patch?
Good idea! Could you please do this?
>
>>>
>>>> And finally please note that for 5.1 we still support Solaris 8 and 9:
>>>>
>>>> http://www.mysql.com/support/supportedplatforms/database.html
>>>>
>>>
>>> What is your point?
>>
>> My point was that if, for example, time() became fast only starting from
>> Solaris 10, we could not simply remove this hack from 5.1, as it would make
>> MySQL 5.1 slower on one of its supported platforms.
>>
>
> Yes, but we still need to fix the bug, don't we? The hack is wrong.
> Also, in the worst case, we could simply use gettimeofday.
Absolutely. I just have tried to point out that we should be careful
when choosing approach to fixing this problem.
--
Dmitry Lenev, Software Developer
Oracle Development SPB/MySQL, www.mysql.com
Are you MySQL certified? http://www.mysql.com/certification
