From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-yx0-f174.google.com ([209.85.213.174]:49429 "EHLO mail-yx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753654Ab0HCDQR (ORCPT ); Mon, 2 Aug 2010 23:16:17 -0400 Received: by yxg6 with SMTP id 6so1464941yxg.19 for ; Mon, 02 Aug 2010 20:16:16 -0700 (PDT) Message-ID: <4C578AFF.2030804@gmail.com> Date: Mon, 02 Aug 2010 23:20:31 -0400 From: Emmanuel MIME-Version: 1.0 To: Marko Ristola CC: VDR User , linux-media@vger.kernel.org Subject: Re: [Q]: any DVB-S2 card which is 45MS/s capable? References: <4C4C475E.5060500@gmail.com> <4C4DDB83.9040009@gmail.com> <4C4ED694.5010505@gmail.com> <4C56CE4D.2060206@kolumbus.fi> In-Reply-To: <4C56CE4D.2060206@kolumbus.fi> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-media-owner@vger.kernel.org List-ID: Marko Ristola a écrit : > > Hi. > > I have written some Mantis bandwidth related > DMA transfer optimizations on June/July this year. > They are now waiting for approval by Manu Abraham. > > Those reduce CPU pressure, increasing the bandwidth > that can be received from the DVB card. 45MS/s bandwidth > support will surely benefit from those patches. > > Main features: > 1. Do one CPU interrupt per 16KB data instead per 4KB data. > My implementation benefits only Mantis cards. > https://patchwork.kernel.org/patch/107036/ > > 2. Remove unnecessary big CPU overhead, when data is delivered > from the DVB card's DMA buffer into Linux kernel's DVB subsystem. > Number 2 reduces the CPU pressure by almost 50%. > This implementation benefits many other Linux supported DVB cards too. > http://patchwork.kernel.org/patch/108274/ > > Those helped with my older single CPU Core computer with 256-QAM, > delivering HDTV channel into the network and watching the > HDTV channel with a faster computer. > > The performance bottlenecks could be seen on the > command line with "perf top". > > I had to increase PCI bus latency setting into 64 too from the BIOS. > Moving DVB device into separate IRQ line with Ethernet card helped too, > because Ethernet card did an interrupt per ethernet packet. > > So if the hardware can deliver 45MS/s data fast enough, software side > can be optimized up > to some point. My patches contain the most easy major optimizations > that I found. > If you can test some of those patches, it might help to get them into > Linux kernel > faster. > > Best regards, > Marko Ristola > OK these optimizations look like a step into the good direction. I guess what is also missing is a tuner which can handle that in DVB-S2, which does not seem obvious. The mantis card can do that? Thx Bye Manu