Date: Fri, 17 Feb 2006 15:44:40 GMT From: Barry Tigner <tigner@msu.edu> To: freebsd-gnats-submit@FreeBSD.org Subject: misc/93485: iostat reports cd0 speeds 2X actual speed Message-ID: <200602171544.k1HFiekS058545@www.freebsd.org> Resent-Message-ID: <200602171550.k1HFoCiJ031406@freefall.freebsd.org>
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>Number: 93485 >Category: misc >Synopsis: iostat reports cd0 speeds 2X actual speed >Confidential: no >Severity: non-critical >Priority: low >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Fri Feb 17 15:50:12 GMT 2006 >Closed-Date: >Last-Modified: >Originator: Barry Tigner >Release: 6.0 release i386 >Organization: Michigan State University >Environment: FreeBSD ESHOP1.PA.MSU.EDU 6.0-RELEASE FreeBSD 6.0-RELEASE #2: Thu Dec 8 08:38:04 EST 2005 root@ESHOP1.PA.MSU.EDU:/usr/src/sys/i386/compile/ESHOP1 i386 >Description: I have a new IDE DVD burner ,Toshiba TSDR5372 16X DL capable. I wanted to investigate the read speeds of file transfers from DVDs. To do this I made a 4.7G DVD with 4 1GB (2^30 bytes)files on it named test1.bin test2.bin test3.bin test4.bin. The system I am using details are: Hardware: Gigabyte GA-K8N-SLI Athlon64/3500 512MB PC3200 ram Toshiba TSDR5372 DVD writer Seagate SATA 160G HD. OS: FreeBSD ESHOP1.PA.MSU.EDU 6.0-RELEASE FreeBSD 6.0-RELEASE #2: Thu Dec 8 08:38:04 EST 2005 root@ESHOP1.PA.MSU.EDU:/usr/src/sys/i386/compile/ESHOP1 i386 KDE 3.5 I mounted the DVD I created using the Toshiba DVD drive as /cdrom. KDE reports the file transfer speeds correctly when I use the KDE desktop to copy the 1GB files from the DVD to the HD. If I run "iostat -w 1" as root while the transfer is occuring , the transfer rate to AD4 shows correctly , however the transfer rate from CD0 shows double the rate it should. Here is an example... ESHOP1# iostat -w1 tty ad4 cd0 pass0 cpu tin tout KB/t tps MB/s KB/t tps MB/s KB/t tps MB/s us ni sy in id 12 66 19.96 3 0.05 63.84 0 0.00 0.00 0 0.00 2 11 64 1 22 224 231 112.00 35 3.83 64.00 118 7.37 0.00 0 0.00 2 0 5 0 94 168 78 126.74 89 11.00 64.00 354 22.10 0.00 0 0.00 5 0 13 2 80 40 78 128.00 127 15.86 64.00 507 31.72 0.00 0 0.00 7 0 14 2 78 56 78 124.58 131 15.92 64.00 507 31.72 0.00 0 0.00 8 0 14 5 74 8 78 125.44 131 16.03 64.00 509 31.84 0.00 0 0.00 5 0 13 4 77 312 78 127.12 128 15.87 64.00 509 31.84 0.00 0 0.00 9 0 14 1 77 16 78 128.00 128 15.98 64.00 511 31.97 0.00 0 0.00 10 0 14 2 74 0 78 124.61 132 16.05 64.00 513 32.09 0.00 0 0.00 8 0 14 0 79 0 78 128.00 129 16.11 64.00 511 31.97 0.00 0 0.00 9 0 14 2 76 24 78 126.26 129 15.89 64.00 507 31.72 0.00 0 0.00 8 0 17 1 75 0 78 127.12 128 15.87 64.00 507 31.72 0.00 0 0.00 7 0 16 2 76 0 78 126.26 129 15.89 64.00 507 31.72 0.00 0 0.00 5 0 16 1 78 40 78 127.12 128 15.87 64.00 509 31.84 0.00 0 0.00 8 0 13 3 76 It can be clearly seen that the CD0 speeds are reported as 2X the AD4 speeds, even though they should be identical since I am just copying from one media to another. >How-To-Repeat: use iostat to monitor transfer rates on the cd0 device. >Fix: be aware of the problem, so you don't get excited about 32MB/S transfer rates from a DVD drive when they are actually 16MB/S. >Release-Note: >Audit-Trail: >Unformatted:
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