Date: Tue, 2 Aug 2011 23:16:52 +0200 From: Jilles Tjoelker <jilles@stack.nl> To: Vlad Galu <dudu@dudu.ro> Cc: hackers@freebsd.org Subject: Re: eliminating a syscall on accept()+ioctl() combo Message-ID: <20110802211652.GA28731@stack.nl> In-Reply-To: <7E99FCF5-66DF-422E-B2FE-28547AF916A7@dudu.ro> References: <E27242EA-A2DD-4CB8-92B6-8B95B3BF3B8E@bitpowder.com> <7E99FCF5-66DF-422E-B2FE-28547AF916A7@dudu.ro>
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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. -- Jilles Tjoelker
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