Date: Tue, 3 Jan 1995 13:19:41 -0600 From: Terry Lee <terry@uivlsi.csl.uiuc.edu> To: hackers@freebsd.org Subject: Topiozone, a new benchmark? Message-ID: <199501031919.AA12159@uivlsi.csl.uiuc.edu>
next in thread | raw e-mail | index | archive | help
I've heard for a long time that busmastering disk controller cards reduce the load on a multi-processing OS, but seeing it makes me a believer! Originally, I had ESDI drives hooked up to an UltraStor 12F (ISA). Recently, I added a BusLogic BT-445C (VLB) host adapter. Since I happened to have an Emulex MD21 ESDI->SCSI bridge, I decided to experiment with it. On my 10MHz ESDI drive, I ran iozone for both the ESDI->12F and the ESDI->MD21->BT445C configurations. Using the MD21 slightly reduces the disk's size and iozone score. OK, that's to be expected (the MD21 uses part of the disk for its own use). But when I ran top during iozone, was I surprised! On my otherwise idle system running X and "iozone 32m 512", the ESDI->12F configuration left only about (my rough estimate) 50% idle CPU time (about 30% of the CPU time was spent in interrupts), while the ESDI->MD21->BT445C configuration left at least 80% idle CPU time (about 1% of the CPU time was spent in interrupts). When running "iozone 32m 8192", the CPU idle time of both configurations improved to about 65% and 95%, respectively. On my 15MHz ESDI drive, the CPU consumption of the ESDI->12F configuration was even worse (I haven't tested the ESDI->MD21->BT445C configuration yet). FYI, my system is a 486DX40 with 16MB of RAM. I'm running the ISA bus at 13.3MHz. The kernel is FreeBSD-current from about a week ago. If my observation holds true for IDE drives and VLB IDE controller cards (I wonder if the faster transfer rate of current IDE drives makes the CPU consumption even worse or not), then this would be a reason to go with busmastering SCSI (with the exception of busmastering EIDE, of course). Now, if I can only get good transfer rates with my 15MHz drive and MD21... But that's another story. :-) Terry Lee terry@uivlsi.csl.uiuc.edu
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199501031919.AA12159>