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Re: CVS commit: src/sys
In article <20111228124228.C4D8614A345%mail.netbsd.org@localhost>,
YAMAMOTO Takashi <yamt%mwd.biglobe.ne.jp@localhost> wrote:
>> On Dec 21, 5:07am, yamt%mwd.biglobe.ne.jp@localhost (YAMAMOTO Takashi)
>> -- Subject: Re: CVS commit: src/sys
>> | why?
>> | i thought the reason of having this as a separate member was performance.
>> All the code paths that use NBIO check bits in so_state... I would like to
>> see the benchmark that proves this.
>it's about the fcntl side, for which you added more locking.
For FIONBIO... Even if you construct a synthetic benchmark that
turns on and off blocking I/O for a socket continuously, and the
locking overhead proves to be larger than the system call overhead
(which it may very well be), I doubt that you'll find any real
program that calls ioctl(so, FIONBIO, ...) frequently enough to
make a difference.
I really think that Andy confused it with FIONREAD (hence the comment),
which can be called quite frequently (and it is still unlocked).
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