SUMMARY: Does disk speed in label influence on perf

From: LBRO <lbro_at_dscc.dk>
Date: Thu, 05 Mar 1998 14:11:24 +0100

     Hi,
     
     The answer seems to be No.
     
     As Nick Batchelor pointed out, the disk speed were used on older UFS
     systems as input for the lowlevel optimization. Having found the
     desired cylinder group by the highlevel optimizer, and knowing the
     freelist bitmap of that cylinder group, it was possible to calculate
     the most suitable free block with respect to the rotational delay of
     the disk and the time needed for the calculations.
     
     It seems that today, such calculations take no time and therefore
     nobody cares about the rotational delay.
     
     It seems to me that AdvFS systems dont know anything of the disk
     geometry atall. This is the direction things go.
     
     Dr. Tom Blinn suggested that it is unlikely that the SCSI drivers use
     any such information. Optimizations that involve knowledge of actual
     geometrical parameters are taken care of by the disk itself. Which
     sounds quite reasonable to me.
     
     Thanks,
     
     Lars Bro (lbro_at_dscc.dk)
Received on Thu Mar 05 1998 - 14:12:48 NZDT

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