From: Nicolas Pitre <nico@fluxnic.net>
To: Lukas Fleischer <lfleischer@lfos.de>
Cc: git@vger.kernel.org, Johannes Sixt <j6t@kdbg.org>
Subject: Re: [PATCH] Refactor recv_sideband()
Date: Tue, 14 Jun 2016 13:55:06 -0400 (EDT) [thread overview]
Message-ID: <alpine.LFD.2.20.1606141347310.1714@knanqh.ubzr> (raw)
In-Reply-To: <CsLdb3qLMBok7CsLebwX38@videotron.ca>
On Tue, 14 Jun 2016, Lukas Fleischer wrote:
> Hi Nicolas,
>
> On Tue, 14 Jun 2016 at 19:09:15, Nicolas Pitre wrote:
> > I just looked again at all the contraptions _I_ wrote (not Junio's) for
> > a reason why I went to such extremes in making this code co complicated.
> >
> > One aspect that is now lost with your patch is the atomic nature of the
> > write. See commit ed1902ef5c for the explanation. You could probably
> > use sprintf() into a temporary buffer and write it in one go to avoid
> > segmented writes from the C library. It's probably not worth having that
> > complex code just to avoid a string copy.
>
> The old code calls fprintf() once per line and so does the new code. The
> only difference is that in the old code, the single parts were
> concatenated manually while the new code tells fprintf() to do the
> concatenation itself while printing. Also note that fprintf() is
> buffered -- so even if the new code would call it more often, it would
> not really matter.
It is not buffered as it writes to stderr. And some C libs do separate
calls to write() for every string format specifier. So "%s%s%c" may end
up calling write() 3 times depending on the implementation. The example
I gave in commit ed1902ef5c is real and I even observed it with strace
back then.
Nicolas
next prev parent reply other threads:[~2016-06-14 17:55 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-13 19:52 [PATCH] Refactor recv_sideband() Lukas Fleischer
2016-06-13 21:07 ` Nicolas Pitre
2016-06-14 13:44 ` Johannes Schindelin
2016-06-14 15:04 ` Nicolas Pitre
2016-06-14 15:30 ` Johannes Schindelin
[not found] ` <Cq7rbYgOpb0CVCq7sbGmpL@videotron.ca>
2016-06-14 16:43 ` Nicolas Pitre
2016-06-14 17:09 ` Nicolas Pitre
[not found] ` <CsLdb3qLMBok7CsLebwX38@videotron.ca>
2016-06-14 17:55 ` Nicolas Pitre [this message]
2016-06-14 18:11 ` Junio C Hamano
2016-06-14 19:11 ` Lukas Fleischer
2016-06-14 19:16 ` Junio C Hamano
[not found] ` <Ct7VbfLfTHEALCt7Wbh8Xs@videotron.ca>
2016-06-14 20:10 ` Nicolas Pitre
2016-06-14 21:00 ` [PATCH v2] " Lukas Fleischer
2016-06-14 21:11 ` Lukas Fleischer
2016-06-14 21:25 ` Junio C Hamano
2016-06-15 3:44 ` Jeff King
[not found] ` <146597489449.32143.1327156804178869158@s-8d3a2dc3.on.site.uni-stuttgart.de>
2016-06-19 10:48 ` Lukas Fleischer
2016-06-24 15:31 ` Jeff King
2016-06-24 17:45 ` Johannes Schindelin
2016-06-24 18:14 ` Jeff King
2016-06-24 18:32 ` Junio C Hamano
2016-06-27 10:58 ` Lukas Fleischer
2016-06-27 15:54 ` Junio C Hamano
2016-06-27 16:16 ` Jeff King
2016-06-27 17:50 ` Junio C Hamano
2016-06-27 20:34 ` Lukas Fleischer
2016-06-27 20:47 ` Nicolas Pitre
2016-06-28 4:01 ` Lukas Fleischer
2016-06-28 5:20 ` Junio C Hamano
2016-06-28 10:04 ` Johannes Schindelin
2016-06-28 10:05 ` Johannes Schindelin
2016-06-28 15:13 ` Junio C Hamano
2016-06-28 16:21 ` Johannes Schindelin
2016-06-24 20:07 ` Dennis Kaarsemaker
2016-06-22 5:29 ` [PATCH v3] " Lukas Fleischer
2016-06-22 15:02 ` Nicolas Pitre
2016-06-22 22:47 ` Nicolas Pitre
2016-06-23 17:35 ` Lukas Fleischer
2016-06-23 18:59 ` Nicolas Pitre
2016-06-28 4:35 ` [PATCH v4] " Lukas Fleischer
2016-06-28 16:57 ` Junio C Hamano
2016-06-28 17:24 ` Junio C Hamano
2016-06-28 17:46 ` Nicolas Pitre
2016-06-28 18:13 ` Junio C Hamano
2016-06-28 18:28 ` Nicolas Pitre
2016-06-28 19:51 ` Junio C Hamano
2016-06-28 20:36 ` Nicolas Pitre
2016-06-28 21:09 ` Junio C Hamano
2016-06-28 21:44 ` Nicolas Pitre
2016-06-28 22:33 ` Junio C Hamano
2016-06-28 22:47 ` Junio C Hamano
2016-06-29 3:00 ` Junio C Hamano
2016-06-29 3:41 ` Nicolas Pitre
2016-06-29 2:02 ` Nicolas Pitre
2016-06-29 16:40 ` Junio C Hamano
2016-06-30 6:16 ` Lukas Fleischer
2016-07-01 20:01 ` Junio C Hamano
2016-07-05 20:35 ` Nicolas Pitre
2016-07-06 21:11 ` Junio C Hamano
2016-07-07 0:56 ` Nicolas Pitre
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