On 01/09/2010 02:57 PM, Stefan Strasser wrote:
Am Saturday 09 January 2010 13:58:35 schrieb Andrey Semashev:
The pointer to the thread-specific data is stored in TLS, last time I checked. And there's no difference in terms of performance in how you store the pointer - via __thread specifier or by manually calling pthread APIs. In case of __thread the compiler will generate the necessary calls to pthread for you, that all you win, AFAIU.
how do you come to that conclusion?
<< __thread int *ptr;
int *get_current_thread_data(){ return ptr; }
<< _Z23get_current_thread_datav: .LFB2: pushl %ebp .LCFI0: movl %gs:ptr@NTPOFF, %eax movl %esp, %ebp .LCFI1: popl %ebp ret
Interesting. It seems that GCC is smarter than I thought. At least on x86. However, __thread doesn't allow to register a cleanup function that is required by Boost.Thread. You could create a dummy TLS with pthread API for that, but then I'm not sure if you could reliably access __thread variables from that function.