Subject: Re: UVM/other problems for desktop users in current?
To: Daniel Carosone <>
From: Oleg Polyanski <>
List: current-users
Date: 12/19/2002 15:21:02
>>>>> "Daniel" == Daniel Carosone writes:

 >> Yep.  And I'd appreciate it if someone explained _why_ decent
 >> IDE with DMA is so bad when compared to SCSI.  Especially if you
 >> only have one device per port and the raw sustained performance
 >> is 30 MB/s or more with only a little CPU loading.

 Daniel> The main reason is that there's only one outstanding
 Daniel> operation to the disk at once.  SCSI disks, with tagged
 Daniel> queueing, allow multiple outstanding requests, that the
 Daniel> drive can respond to in the order that best suits its
 Daniel> internal state (disk head position, mostly).

  This isn't true, most modern IDE hard drive have the tagged
  queueing ability.