From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from emh01.mail.saunalahti.fi ([62.142.5.107]:54232 "EHLO emh01.mail.saunalahti.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932341Ab0HCQDR convert rfc822-to-8bit (ORCPT ); Tue, 3 Aug 2010 12:03:17 -0400 Message-ID: <4C583DC0.9090405@kolumbus.fi> Date: Tue, 03 Aug 2010 19:03:12 +0300 From: Marko Ristola MIME-Version: 1.0 To: Emmanuel 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> <4C578AFF.2030804@gmail.com> In-Reply-To: <4C578AFF.2030804@gmail.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8BIT Sender: linux-media-owner@vger.kernel.org List-ID: 03.08.2010 06:20, Emmanuel wrote: > 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? According to Internet shops it can. Manu Abraham has implemented the DVB-S2 support earlier than this summer, so with my small improvements it could perform better. Here is a page about DVB-S2 cards that work somehow with Linux: http://www.linuxtv.org/wiki/index.php/DVB-S2_PCI_Cards I myself have been testing only with 9600 MS/s with terrestial DVB-C, so I have no experience with DVB-S2. With 9600 MS/s and HDTV, the whole system must work, including VDR with it's components, not only the PCI DVB card. With SDTV, any hardware will do. Regards, Marko Ristola > Thx > Bye > Manu >