stdcxx-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Martin Sebor <se...@roguewave.com>
Subject Re: stdcxx 4.2.0/4.1.3 binary incompatibility on Linux
Date Wed, 17 Oct 2007 20:06:37 GMT
Mark Brown wrote:
> On 10/17/07, Martin Sebor <sebor@roguewave.com> wrote:
>> Okay, I've got it:
>>
>>     http://issues.apache.org/jira/browse/STDCXX-162
>>
>> Damn that was hard!
>>
>> So, what do we do? Going back to using a mutex for strings would
>> be *huge* performance hit on one of the most popular platforms
>> (if not the most popular one), but then again, keeping the status
>> quo will break binary compatibility on the (now) most popular
>> platform.
>>
>> Opinions?
> 
> Maybe it isn't as bad as you think. Have you done any measurements of
> the performance difference between the previous version and 4.2.0?

It is quite bad. Here are timings for 4 threads (running on
a 4 CPU dual core Xeon) copying the same global string object
5 million times:

                4.1.x        4.2.0
     real    0m38.464s    0m 8.660s
     user    0m26.685s    0m33.655s
     sys     1m54.129s    0m 0.001s

I was hoping that stdcxx 4.1.2 wouldn't build on x86_64 and
that the platform would be new for 4.1.3 (and could thought
of as experimental, giving us a possible excuse to break
compatibility) but no such luck. It builds fine and has the
mutex in it, just like 4.1.3.

Martin

> 
> -- Mark


Mime
View raw message