Date: Sun, 8 Oct 1995 12:04:47 +1000 From: Bruce Evans <bde@zeta.org.au> To: gibbs@freefall.freebsd.org, se@ZPR.Uni-Koeln.DE Cc: hackers@freebsd.org, ken@rflab1.gtri.gatech.edu Subject: Re: VLB Disk Controllers Message-ID: <199510080204.MAA11808@godzilla.zeta.org.au>
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>>Something I just noticed is the big difference >>in results I get using /dev/rsd0 vs. /dev/rsd0a: >> >># disklatency /dev/rsd0 >>Command overhead is 719 usec (time_4096 = 1198, time_8192 = 1677) >>transfer speed is 8.55617e+06 bytes/sec >> >># disklatency /dev/rsd0a >>Command overhead is 807 usec (time_4096 = 1272, time_8192 = 1738) >>transfer speed is 8.80588e+06 bytes/sec >> >>Any ideas ??? >Slice code? It may be that we take some steps to validate the disklable >for that partition, do additional range checks etc. Bruce probably >knows. It shouldn't be that large. Perhaps the first 16 sectors of rsd0a span a physical track boundary and the drive doesn't handle this well. Perhaps the benchmark is less accurate than you expect. It takes a difference of two times that may be close together so the variance of the difference may be large. Bruce
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