that deferring reads and re-ordering them could reduce head movement and improve throughput, but most disk controllers do this as a matter of course now
That is impossible unless the application uses some kind of asynchronous IO in order to queue several read operations and let the OS/hardware handle them in some order that minimizes head movement delays.

But for common applications using synchronous IO, the app will ask for some data, wait for the OS to fulfill the request, ask for some other data, etc., so there is no way for the OS to reorder the operations.

Another matter is considering a multithreaded/multiprocess environment where the OS/hardware can reorder the IO operations queued at any point in time by all the running threads.

In reply to Re^2: Efficiency of seek by salva
in thread Efficiency of seek by llancet

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.