[PATCH v2] Make bindresvport() function to multithread-safe

[Peng Haitao]

On 09/24/2012 11:08 PM, Carlos O'Donell wrote:
> Define a macro in an internal header that for generic unix uses __getpid,
> and for Linux it is overriden by a linux-specific header that defines
> that macro as a combination of either INTERNAL_SYSCALL/INLINE_SYSCALL.
> 

Thanks.
I have sent v4 patch, please review.

> The whole point of that code is to create a hash function from which
> to start looking for free ports. If the hash function has poor spread
> because you only have __getpid in your OS, then that's not a serious
> issue.
> 
> You will still need to present performance data to show how these changes
> effect the performance of the original non-thread-safe version.
> 

The single-thread test result is as follows:
Before the patch, execute the test program with 100 times:

# perf stat -r 100 -e instructions -- ./bindresvport_test > /dev/null

 Performance counter stats for './bindresvport_test' (100 runs):

       106,594,501 instructions              #    0.00  insns per cycle          ( +-  0.35% )

       0.028158698 seconds time elapsed                                          ( +-  0.88% )


After the patch, execute the test program with 100 times:

# perf stat -r 100 -e instructions -- ./bindresvport_test > /dev/null

 Performance counter stats for './bindresvport_test' (100 runs):

       104,938,026 instructions              #    0.00  insns per cycle          ( +-  0.44% )

       0.027621324 seconds time elapsed                                          ( +-  0.94% )



The multi-threaded test result is as follows:
Before the patch, execute the test program with 100 times:

# perf stat -r 100 -e instructions -- ./bindresvport_mul_test > /dev/null
bindresvport: Address already in use
...

 Performance counter stats for './bindresvport_mul_test' (100 runs):

       116,481,478 instructions              #    0.00  insns per cycle          ( +-  0.25% )

       0.023839225 seconds time elapsed                                          ( +-  2.04% )


After the patch, execute the test program with 100 times:
# perf stat -r 100 -e instructions -- ./bindresvport_mul_test > /dev/nullbindresvport: Address already in use
bindresvport: Address already in use
...

 Performance counter stats for './bindresvport_mul_test' (100 runs):

       124,069,053 instructions              #    0.00  insns per cycle          ( +-  0.32% )

       0.021486935 seconds time elapsed                                          ( +-  0.84% )


The single-thread test program is bindresvport_test.c
The multi-thread test program is bindresvport_mul_test.c


-- 
Best Regards,
Peng
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