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From: Vlad Galu <dudu@dudu.ro>
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Date: Tue, 2 Aug 2011 23:45:11 +0200
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To: Jilles Tjoelker <jilles@stack.nl>
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Subject: Re: eliminating a syscall on accept()+ioctl() combo
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On Aug 2, 2011, at 11:16 PM, Jilles Tjoelker wrote:
> On Mon, Aug 01, 2011 at 08:11:04AM +0200, Vlad Galu wrote:
>> On Jul 31, 2011, at 9:59 PM, Bernard van Gastel wrote:
>>> I want to reduce the number of syscalls for my networking
>>> application. The app handles incoming connections with the
>>> 'accept()' system call. Is there a way to specify to accept() that
>>> the newly created file descriptors should be non-blocking (FIONBIO)?
>>> This will avoid an ioctl() after the accept(). Thanks!
> 
>> You can make your listening socket non-blocking. Newly created file
>> descriptors will inherit that property. However, that will require you
>> to select()/poll()/kqueue() for that descriptor as well, instead of
>> simply blocking in accept().
> 
> This is documented FreeBSD behaviour and common across BSDs, but is not
> portable. POSIX leaves it unspecified what the non-blocking state of the
> new socket is and in fact Linux always makes the new socket blocking
> (unless you request non-blocking using their new accept4() call).
> 
> Because this portability issue can be very subtle, I suggest not blindly
> relying on it.


Oh, ok. I wasn't aware. Thanks for the heads-up.

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