From: "John W. Linville" <linville@tuxdriver.com>
To: Martijn van Oosterhout <kleptog@svana.org>
Cc: Mandeep Sandhu <Mandeep_Sandhu@infosys.com>,
dima@s2io.com, Jeff Garzik <jgarzik@pobox.com>,
linux-newbie@vger.kernel.org, linux-net@vger.kernel.org,
linux-kernel@vger.kernel.org,
kernelnewbies <kernelnewbies@nl.linux.org>
Subject: Re: zero copy issue while receiving the data (counter part of sendfil e)
Date: Wed, 22 Dec 2004 11:06:27 -0500 [thread overview]
Message-ID: <20041222160625.GB19449@tuxdriver.com> (raw)
In-Reply-To: <20041222155003.GA29278@svana.org>
On Wed, Dec 22, 2004 at 04:50:05PM +0100, Martijn van Oosterhout wrote:
> Generally, reading from memory takes time because the CPU has to wait,
> writing is free since it can be deferred in the cache (in theory
> indefinitly) until there's free cycle.
I'm not sure I'd call that "free" -- executing the instructions for
the write has a non-zero cost.
Still, it is significantly cheaper than the read...
John
--
John W. Linville
linville@tuxdriver.com
--
Kernelnewbies: Help each other learn about the Linux kernel.
Archive: http://mail.nl.linux.org/kernelnewbies/
FAQ: http://kernelnewbies.org/faq/
WARNING: multiple messages have this Message-ID (diff)
From: "John W. Linville" <linville@tuxdriver.com>
To: Martijn van Oosterhout <kleptog@svana.org>
Cc: Mandeep Sandhu <Mandeep_Sandhu@infosys.com>,
dima@s2io.com, Jeff Garzik <jgarzik@pobox.com>,
linux-newbie@vger.kernel.org, linux-net@vger.kernel.org,
linux-kernel@vger.kernel.org,
kernelnewbies <kernelnewbies@nl.linux.org>
Subject: Re: zero copy issue while receiving the data (counter part of sendfil e)
Date: Wed, 22 Dec 2004 11:06:27 -0500 [thread overview]
Message-ID: <20041222160625.GB19449@tuxdriver.com> (raw)
In-Reply-To: <20041222155003.GA29278@svana.org>
On Wed, Dec 22, 2004 at 04:50:05PM +0100, Martijn van Oosterhout wrote:
> Generally, reading from memory takes time because the CPU has to wait,
> writing is free since it can be deferred in the cache (in theory
> indefinitly) until there's free cycle.
I'm not sure I'd call that "free" -- executing the instructions for
the write has a non-zero cost.
Still, it is significantly cheaper than the read...
John
--
John W. Linville
linville@tuxdriver.com
next prev parent reply other threads:[~2004-12-22 16:06 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-12-21 16:35 zero copy issue while receiving the data (counter part of sen dfil e) Rajat Jain, Noida
2004-12-21 16:35 ` Rajat Jain, Noida
2004-12-21 17:22 ` Dmitry Yusupov
2004-12-21 17:22 ` Dmitry Yusupov
2004-12-21 19:30 ` Jeff Garzik
2004-12-21 19:30 ` Jeff Garzik
2004-12-21 19:43 ` Dmitry Yusupov
2004-12-21 19:43 ` Dmitry Yusupov
2004-12-22 8:21 ` zero copy issue while receiving the data (counter part of sendfil e) Mandeep Sandhu
2004-12-22 8:21 ` Mandeep Sandhu
2004-12-22 15:50 ` Martijn van Oosterhout
2004-12-22 16:06 ` John W. Linville [this message]
2004-12-22 16:06 ` John W. Linville
-- strict thread matches above, loose matches on Subject: below --
2004-12-16 14:08 Rajat Jain, Noida
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