Yes, i know that and i agree with them. that was the reason, why my disk is tiled on first physical Gigabyte for Swap, and the rest for the system....
my target was to compare 2 Versions not 2 Os-Types like FreeBSD and Linux, but FreeBSD and FreeBSD, in cases RELENG_4 with RELENG_5. so that the little difference between the different places for files, remember i install everytime at the beginning of second Gig on disk, should be flawlessy and not make the results so big, that the RELENG_4 has the double of speed from RELENG_5! best regards michael 2005/6/28, Paul Mather <[EMAIL PROTECTED]>: > On Tue, 2005-06-28 at 11:21 +0200, Roman Neuhauser wrote: > > # [EMAIL PROTECTED] / 2005-06-21 16:51:10 +0200: > > > For accurate measurements and comparisons, you have to make > > > sure to use _exactly_ the same physical location on the > > > disk. > > > > No you don't. You want to make a side-by-side comparison > > of two products, and if one of them underperforms, it just > > underperforms. You cannot use a poor location selection > > strategy in the driver as an excuse for poor operation. > > The point people are making is that location can have a significant > effect on performance, and so should not be dismissed out of hand. > > Here is what I get when I run diskinfo on one of the (somewhat elderly) > disks I use in my desktop system (this is a drive I use for data, and it > is idle): > > zappa# diskinfo -tv /dev/ad4 > /dev/ad4 > 512 # sectorsize > 25590620160 # mediasize in bytes (24G) > 49981680 # mediasize in sectors > 49585 # Cylinders according to firmware. > 16 # Heads according to firmware. > 63 # Sectors according to firmware. > > Seek times: > Full stroke: 250 iter in 5.159189 sec = 20.637 msec > Half stroke: 250 iter in 4.206125 sec = 16.825 msec > Quarter stroke: 500 iter in 7.151951 sec = 14.304 msec > Short forward: 400 iter in 2.794380 sec = 6.986 msec > Short backward: 400 iter in 4.135579 sec = 10.339 msec > Seq outer: 2048 iter in 0.332711 sec = 0.162 msec > Seq inner: 2048 iter in 0.363152 sec = 0.177 msec > Transfer rates: > outside: 102400 kbytes in 7.677977 sec = 13337 kbytes/sec > middle: 102400 kbytes in 9.151475 sec = 11189 kbytes/sec > inside: 102400 kbytes in 14.345492 sec = 7138 kbytes/sec > > Note how the transfer rate for the "outside" is almost twice that of the > "inside." Suppose I run tests on two different operating systems, one > of which resides in a partition on the "inside" portion and the other in > one on the "outside" portion. (Note that however good or bad it may be, > the "location selection strategy in the driver" can only lay out data > within the confines of the partition.) Now, I do a "dd" test and find > that the "outside" OS is almost twice as fast as the other. Would it be > wise to conclude that the slower OS is woefully inefficient compared to > the faster one? Suppose both tests turn out to take roughly the same > time. Should I conclude that the OS residing on the "inside" is just as > efficient as the other OS? > > Cheers, > > Paul. > -- > e-mail: [EMAIL PROTECTED] > > "Without music to decorate it, time is just a bunch of boring production > deadlines or dates by which bills must be paid." > --- Frank Vincent Zappa > _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "[EMAIL PROTECTED]"
