From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sat, 30 Jun 2001 11:49:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sat, 30 Jun 2001 11:49:38 -0400 Received: from smtp3.xs4all.nl ([194.109.127.132]:14352 "EHLO smtp3.xs4all.nl") by vger.kernel.org with ESMTP id ; Sat, 30 Jun 2001 11:49:29 -0400 Message-ID: <3B3DF519.FDC11523@vioro.nl> Date: Sat, 30 Jun 2001 17:49:45 +0200 From: Marc Kool Organization: Vioro Consultancy BV X-Mailer: Mozilla 4.76 [en] (X11; U; Linux 2.4.5 i686) X-Accept-Language: en, nl, pt-BR, pt MIME-Version: 1.0 To: linux-kernel@vger.kernel.org Subject: bug? dd on /dev/sdb makes system *incredibly* slow 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 Hi, I don't where else to send this ... so please send it to the right person if this is the wrong address. Below is a bug report. Please let me know if you can look at it. Thanks Marc [1.] One line summary of the problem: dd if=/dev/sdb of=/dev/null bs=64k makes fast system *slow* [2.] Full description of the problem/report: I had 2 I/O errors on my second SCSI disk (/dev/sdbx). To verify the whole disk, I did dd if=/dev/sdb of=/dev/null bs=64k It turned the fast system into a 4.77 MHz XT [3.] Keywords (i.e., modules, networking, kernel): kernel, raw I/O, SCSI disk, buffering [4.] Kernel version (from /proc/version): Linux version 2.4.5 (root@adamsrv1) (gcc version 2.95.3 20010315 (release)) #12 Thu Jun 28 02:06:13 CEST 2001 [5.] Output of Oops.. message (if applicable) with symbolic information resolved (see Documentation/oops-tracing.txt) no OOPS [6.] A small shell script or example program which triggers the problem (if possible) dd if=/dev/sdb of=/dev/null bs=64k [7.] Environment [7.1.] Software (add the output of the ver_linux script here) Linux 2.4.5 no modifications [7.2.] Processor information (from /proc/cpuinfo): processor : 0 vendor_id : GenuineIntel cpu family : 6 model : 5 model name : Pentium II (Deschutes) stepping : 2 cpu MHz : 400.914 cache size : 512 KB fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 2 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 sep mtrr pge mca cmov pat pse36 mmx fxsr bogomips : 799.53 [7.3.] Module information (from /proc/modules): vmnet 18272 3 vmmon 18832 0 (unused) These are VMware modules [7.4.] Loaded driver and hardware information (/proc/ioports, /proc/iomem) 0000-001f : dma1 0020-003f : pic1 0040-005f : timer 0060-006f : keyboard 0070-007f : rtc 0080-008f : dma page reg 00a0-00bf : pic2 00c0-00df : dma2 00f0-00ff : fpu 01f0-01f7 : ide0 02f8-02ff : serial(auto) 03c0-03df : vga+ 03f6-03f6 : ide0 03f8-03ff : serial(auto) 0cf8-0cff : PCI conf1 4000-403f : Intel Corporation 82371AB PIIX4 ACPI 5000-501f : Intel Corporation 82371AB PIIX4 ACPI c000-cfff : PCI Bus #01 d000-d01f : Intel Corporation 82371AB PIIX4 USB d000-d01f : usb-uhci d400-d47f : 3Com Corporation 3c905B 100BaseTX [Cyclone] d400-d47f : eth0 d800-d87f : Eicon Technology Corporation DIVA 20 dc00-dc1f : Eicon Technology Corporation DIVA 20 dc00-dc1f : diva isdn e000-e0ff : Adaptec AIC-7881U f000-f00f : Intel Corporation 82371AB PIIX4 IDE 00000000-0009ffff : System RAM 000a0000-000bffff : Video RAM area 000c0000-000c7fff : Video ROM 000c8000-000cc7ff : Extension ROM 000f0000-000fffff : System ROM 00100000-0ffeffff : System RAM 00100000-00268e87 : Kernel code 00268e88-002f175f : Kernel data 0fff0000-0fff2fff : ACPI Non-volatile Storage 0fff3000-0fffffff : ACPI Tables e4000000-e7ffffff : PCI Bus #01 e4000000-e4003fff : Matrox Graphics, Inc. MGA G200 AGP e5000000-e57fffff : Matrox Graphics, Inc. MGA G200 AGP e8000000-ebffffff : Intel Corporation 440BX/ZX - 82443BX/ZX Host bridge ed000000-edffffff : PCI Bus #01 ed000000-edffffff : Matrox Graphics, Inc. MGA G200 AGP ef000000-ef00007f : 3Com Corporation 3c905B 100BaseTX [Cyclone] ef001000-ef001fff : Adaptec AIC-7881U ef001000-ef001fff : aic7xxx ef002000-ef00207f : Eicon Technology Corporation DIVA 20 ffff0000-ffffffff : reserved [7.5.] PCI information ('lspci -vvv' as root) 00:00.0 Host bridge: Intel Corporation 440BX/ZX - 82443BX/ZX Host bridge (rev 02) Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- Status: Cap+ 66Mhz- UDF- FastB2B- ParErr- DEVSEL=medium >TAbort- SERR- 00:01.0 PCI bridge: Intel Corporation 440BX/ZX - 82443BX/ZX AGP bridge (rev 02) (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+ 00:07.0 ISA bridge: Intel Corporation 82371AB PIIX4 ISA (rev 02) 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- [disabled] [size=64K] Capabilities: [dc] Power Management version 1 Flags: PMEClk- DSI+ D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-) Status: D0 PME-Enable- DSel=0 DScale=0 PME- Capabilities: [f0] AGP version 1.0 Status: RQ=31 SBA+ 64bit- FW- Rate=x1,x2 Command: RQ=31 SBA+ AGP+ 64bit- FW- Rate=x2 [7.6.] SCSI information (from /proc/scsi/scsi) Attached devices: Host: scsi0 Channel: 00 Id: 00 Lun: 00 Vendor: IBM Model: DGHS09U Rev: 03B0 Type: Direct-Access ANSI SCSI revision: 03 Host: scsi0 Channel: 00 Id: 01 Lun: 00 Vendor: IBM Model: DGHS09U Rev: 03B0 Type: Direct-Access ANSI SCSI revision: 03 Host: scsi0 Channel: 00 Id: 03 Lun: 00 Vendor: HP Model: C1537A Rev: L708 Type: Sequential-Access ANSI SCSI revision: 02 [7.7.] Other information that might be relevant to the problem (please look in /proc and include all information that you think to be relevant): I Have Linux 2.4.x on /dev/sdb and Linux 2.0.x on sda. /dev/sda is not used by any program. /dev/sdb contains / /boot swap and /local. My system is reasonably fast with 400 MHz Pentium II, 256 MB memory and 2 * 9GB SCSI disks When the system is idle, top shows 4M free, 91M buffers, 110M cached test A. After dd is started (on an idle system) on the idle disk (/dev/sda), top shows after a short while 4M free 2104M buffers, 17M cached. interactive performance: barely acceptable (typing this in netscape is slow and the window manager responds after 8 seconds). The CPU is 90% idle. test B. After dd is started on the disk where the OS and programs are (/dev/sdb) The interactive response is worse and still the CPU is 90% idle. Even the mouse responds late. Doing a additional compilation job in the background brings the system on its knees where interaction with netscape is almost impossible. top shows again 4M free 204M buffers, 17M cached. It seems that the I/O for the raw device takes too many buffers which are not freed in time (they are freed, of course, since dd completes normally after reading the 9 GB). The abnormal consumption of buffers makes the system slow. In a normal day, one does not quickly do dd on a raw disk, so you might be tempted to give this issue a low priority but there are applications like VMware and Sybase that use raw partitions.