From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934024AbXC1IjA (ORCPT ); Wed, 28 Mar 2007 04:39:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S934015AbXC1IjA (ORCPT ); Wed, 28 Mar 2007 04:39:00 -0400 Received: from smtp4-g19.free.fr ([212.27.42.30]:34280 "EHLO smtp4-g19.free.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934014AbXC1Ii6 (ORCPT ); Wed, 28 Mar 2007 04:38:58 -0400 X-Greylist: delayed 57946 seconds by postgrey-1.27 at vger.kernel.org; Wed, 28 Mar 2007 04:38:57 EDT Message-ID: <460A297A.2030200@free.fr> Date: Wed, 28 Mar 2007 10:38:18 +0200 From: John User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8.0.8) Gecko/20061108 SeaMonkey/1.0.6 MIME-Version: 1.0 To: linux-kernel@vger.kernel.org CC: Lee Revell , mingo@elte.hu, akpm@osdl.org, linux-apps@vger.kernel.org, linux.kernel@free.fr Subject: Re: 2.6.20.3-rt8 - DMA suffers excessive delay periodically References: <46094728.40300@free.fr> <75b66ecd0703271341x34463c49w64bdac21a9741355@mail.gmail.com> In-Reply-To: <75b66ecd0703271341x34463c49w64bdac21a9741355@mail.gmail.com> Content-Type: multipart/mixed; boundary="------------050102030609040301070504" Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org This is a multi-part message in MIME format. --------------050102030609040301070504 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit Lee Revell wrote: > John wrote: > >> I'm runnning 2.6.20.3 patched with -rt8 (and glibc 2.3.6). >> http://people.redhat.com/mingo/realtime-preempt/older/patch-2.6.20-rt8 >> >> I've written a program to highlight a phenomenon I don't understand. >> >> This system includes a PCI board that provides data at ~38 Mbit/s. >> I request data in lumps of 1316 bytes. >> In other words, a new request should complete every 277 µs. >> >> However, if I time stamp each packet as soon as I receive it, I notice >> that almost exactly every 2 seconds, the packet is received 30-100 >> microseconds late. > > Sounds like periodic SMM traps. There's not much you can do about > them other than to avoid such hardware if you have tight RT > constraints. The RTAI people have some code to disable SMM but it > does not work on all chipsets and may render some of your hardware > inoperable. The motherboard is an EBC-2000T. http://www.adlinktech.com/PD/web/PD_detail.php?pid=213 lspci -vvv output provided as an attachment. VIA Pro133T chipset: http://www.via.com.tw/en/products/chipsets/legacy/pro133/ http://www.via.com.tw/en/products/chipsets/legacy/pro133a/ dmesg mentions: DMI 2.3 present. Is this related to SMM? As far as I can tell, the BIOS is Phoenix AwardBIOS v6.00PG. Would someone know how to disable SMM in this BIOS? > Is this a laptop? They are plagued with SMM problems... No it is an "indutrial" motherboard. Although I don't know what makes it "industrial". Regards. --------------050102030609040301070504 Content-Type: text/plain; name="adlink.lspci" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="adlink.lspci" 00:00.0 Host bridge: VIA Technologies, Inc. VT82C693A/694x [Apollo PRO133x] (rev c4) Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- Status: Cap+ 66Mhz- UDF- FastB2B- ParErr- DEVSEL=medium >TAbort- SERR- Capabilities: [c0] Power Management version 2 Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-) Status: D0 PME-Enable- DSel=0 DScale=0 PME- 00:01.0 PCI bridge: VIA Technologies, Inc. VT82C598/694x [Apollo MVP3/Pro133x AGP] (prog-if 00 [Normal decode]) Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- Status: Cap+ 66Mhz+ UDF- FastB2B- ParErr- DEVSEL=medium >TAbort- SERR- Reset- FastB2B- Capabilities: [80] Power Management version 2 Flags: PMEClk- DSI- D1+ D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-) Status: D0 PME-Enable- DSel=0 DScale=0 PME- 00:07.0 ISA bridge: VIA Technologies, Inc. VT82C686 [Apollo Super South] (rev 40) Subsystem: VIA Technologies, Inc. VT82C686/A PCI to ISA Bridge Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping+ SERR- FastB2B- Status: Cap+ 66Mhz- UDF- FastB2B- ParErr- DEVSEL=medium >TAbort- SERR- TAbort- SERR- TAbort- SERR- TAbort- SERR- TAbort- SERR- TAbort- SERR- TAbort- SERR- TAbort- SERR- TAbort- SERR- Reset- FastB2B- Capabilities: [dc] Power Management version 2 Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-) Status: D0 PME-Enable- DSel=0 DScale=0 PME- Bridge: PM- B3+ 02:0f.0 Multimedia controller: PLX Technology, Inc. Francois Subsystem: PHILIPS Business Electronics B.V.: Unknown device d128 Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- Status: Cap+ 66Mhz+ UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort- SERR-