Messages in this thread | ![/](/images/icornerl.gif) | | Date | Sun, 13 Apr 2003 14:03:41 -0400 | From | Chuck Ebbert <> | Subject | Re: Benefits from computing physical IDE disk geometry? |
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Nick Piggin wrote:
>> >> Any good SCSI drive knows the physical geometry of the disk and can >> therefore optimally schedule reads and writes. Although necessary features, >> like read queueing, are also available in the current SATA spec, I'm not >> sure most drives will implement it, at least not very well. >> > The "continuous" nature of drive addressing means that the kernel > can do a fine job seek-wise. Due to write caches and read track > buffers, rotational scheduling (which could be done if we knew > geometry) would provide too little gain for the complexity. I would > say that for most workloads you wouldn't see any difference. (IMO)
OTOH you can come up with scenarios like, say, a DBMS doing 16K page aligned IO to raw devices where you might see big gains from making sure those 16K chunks didn't cross a physical cylinder boundary.
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