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From:Davi Arnaut Date:December 16 2010 11:51am
Subject:Re: bzr commit into mysql-5.1-bugteam branch (davi:3520) Bug#42054
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On 12/16/10 9:50 AM, Dmitry Lenev wrote:
> 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?

Will do.

>>
>>>>
>>>>> 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.
>

Aha! OK. :-)
Thread
bzr commit into mysql-5.1-bugteam branch (davi:3520) Bug#42054Davi Arnaut14 Dec
Re: bzr commit into mysql-5.1-bugteam branch (davi:3520) Bug#42054Magne Mæhre15 Dec
Re: bzr commit into mysql-5.1-bugteam branch (davi:3520) Bug#42054Dmitry Lenev16 Dec
  • Re: bzr commit into mysql-5.1-bugteam branch (davi:3520) Bug#42054Davi Arnaut16 Dec
    • Re: bzr commit into mysql-5.1-bugteam branch (davi:3520) Bug#42054Dmitry Lenev16 Dec
      • Re: bzr commit into mysql-5.1-bugteam branch (davi:3520) Bug#42054Davi Arnaut16 Dec
        • Re: bzr commit into mysql-5.1-bugteam branch (davi:3520) Bug#42054Dmitry Lenev16 Dec
          • Re: bzr commit into mysql-5.1-bugteam branch (davi:3520) Bug#42054Davi Arnaut16 Dec