From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751247AbVHXR0h (ORCPT ); Wed, 24 Aug 2005 13:26:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751249AbVHXR0h (ORCPT ); Wed, 24 Aug 2005 13:26:37 -0400 Received: from web33309.mail.mud.yahoo.com ([68.142.206.124]:62570 "HELO web33309.mail.mud.yahoo.com") by vger.kernel.org with SMTP id S1751247AbVHXR0h (ORCPT ); Wed, 24 Aug 2005 13:26:37 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=Message-ID:Received:Date:From:Reply-To:Subject:To:Cc:In-Reply-To:MIME-Version:Content-Type:Content-Transfer-Encoding; b=LemCofWJ2FzT5csVlWwgr1ynxBNJPGUI+ZK9Kmrk5fHPYS9URGc7cDcuaJwozxsFrD0dsDCliLkTqHjUbDs1NpO40Kb/B3WzSXF3GhKxxVFey8kP+q5axCz4JzJ4lumefsYRClFXpZQYMLp/Upul7geQNUiSLT+FdtY2zC3BQm0= ; Message-ID: <20050824172631.11829.qmail@web33309.mail.mud.yahoo.com> Date: Wed, 24 Aug 2005 10:26:31 -0700 (PDT) From: Danial Thom Reply-To: danial_thom@yahoo.com Subject: Re: 2.6.12 Performance problems To: Jesper Juhl Cc: linux-kernel@vger.kernel.org In-Reply-To: <9a87484905082409356c549512@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org --- Jesper Juhl wrote: > On 8/24/05, Danial Thom > wrote: > > --- Patrick McHardy wrote: > > > > > Danial Thom wrote: > > > > I think part of the problem is the > continued > > > > misuse of the word "latency". Latency, in > > > > language terms, means "unexplained > delay". > > > Its > > > > wrong here because for one, its > explainable. > > > But > > > > it also depends on your perspective. The > > > > "latency" is increased for kernel tasks, > > > while it > > > > may be reduced for something that is > getting > > > the > > > > benefit of preempting the kernel. So you > > > really > > > > can't say "the price of reduced latency > is > > > lower > > > > throughput", because thats simply > backwards. > > > > You've increased the kernel tasks latency > by > > > > allowing it to be pre-empted. Reduced > latency > > > > implies higher efficiency. All you've > done > > > here > > > > is shift the latency from one task to > > > another, so > > > > there is no reduction overall, in fact > there > > > is > > > > probably a marginal increase due to the > > > overhead > > > > of pre-emption vs doing nothing. > > > > > > If instead of complaining you would provide > the > > > information > > > I've asked for two days ago someone might > > > actually be able > > > to help you. > > > > Because gaining an understanding of how the > > settings work is better than having 30 guys > > telling me to tune something that is only > going > > to make a marginal difference. I didn't ask > you > > to tell me what was wrong with my setup, only > > whether its expected that 2.6 would be less > > useful in a UP setup than 2.4, which I think > > you've answered. > > > > I hope you're implying that the answer is; no, > it's not expected that > 2.6 is less useful in a UP setup than 2.4 :-) I think the concensus is that 2.6 has made trade offs that lower raw throughput, which is what a networking device needs. So as a router or network appliance, 2.6 seems less suitable. A raw bridging test on a 2.0Ghz operton system: FreeBSD 4.9: Drops no packets at 900K pps Linux 2.4.24: Starts dropping packets at 350K pps Linux 2.6.12: Starts dropping packets at 100K pps Now the 2.6.12 keyboard is always nice and snappy, but thats not what I need. I can't have a box drop traffic if some admin decides to recompile some application. Linux is fine on low-medium speed networks, but at a certain capacity, depending on the specs of the machine of course, linux drops packets. If I do a "make install" in BSD when on a busy network, it takes a long time, but it doesn't drop packets. Linux compiles a lot faster, but it drops buckets of packets. Its just not the priority thats needed for a networking device. Danial ____________________________________________________ Start your day with Yahoo! - make it your home page http://www.yahoo.com/r/hs