From mboxrd@z Thu Jan 1 00:00:00 1970 From: "John W. Linville" Subject: Re: zero copy issue while receiving the data (counter part of sendfil e) Date: Wed, 22 Dec 2004 11:06:27 -0500 Message-ID: <20041222160625.GB19449@tuxdriver.com> References: <267988DEACEC5A4D86D5FCD780313FBB02C66FCA@exch-03.noida.hcltech.com> <1103649767.7217.100.camel@beastie> <41C879CB.3040600@pobox.com> <1103658190.7217.121.camel@beastie> <1103703718.3775.93.camel@samish.india.ascend.com> <20041222155003.GA29278@svana.org> Mime-Version: 1.0 Return-path: Content-Disposition: inline In-Reply-To: <20041222155003.GA29278@svana.org> Sender: kernelnewbies-bounce@nl.linux.org Errors-to: kernelnewbies-bounce@nl.linux.org List-help: List-unsubscribe: List-software: Ecartis version 1.0.0 List-Id: List-subscribe: List-owner: List-post: List-archive: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Martijn van Oosterhout Cc: Mandeep Sandhu , dima@s2io.com, Jeff Garzik , linux-newbie@vger.kernel.org, linux-net@vger.kernel.org, linux-kernel@vger.kernel.org, kernelnewbies 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/