Date: Thu, 18 Apr 1996 13:55:26 -0700 From: "Justin T. Gibbs" <gibbs@freefall.freebsd.org> To: Jaye Mathisen <mrcpu@cdsnet.net> Cc: hackers@freebsd.org, gibbs@freebsd.org Subject: Re: QUEUE_FULL_ENABLE option really work? Message-ID: <199604182055.NAA08285@freefall.freebsd.org> In-Reply-To: Your message of "Thu, 18 Apr 1996 13:01:06 PDT." <Pine.NEB.3.92.960418125843.19574E-100000@schizo.cdsnet.net>
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The option is QUEUE_FULL_SUPPORTED and it does what its supposed to. It increases the number of tags allowed per device to 4 instead of the default of two. >I just turned it off on a box with a 2940, and across the board I'm >picking up 700-800k/s improvements: > >old: > >IOZONE performance measurements: > 1168024 bytes/second for writing the file > 4445767 bytes/second for reading the file > > >new: > >IOZONE performance measurements: > 1790285 bytes/second for writing the file > 5332448 bytes/second for reading the file But your random I/O scores will decrease since the drive will only have at max two I/Os to sort in order to reduce seeks. If you're only interested in sequential I/O, you might as well turn off tagged queueing since for some devices you will get better results. -- Justin T. Gibbs =========================================== FreeBSD: Turning PCs into workstations ===========================================
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