title: Read file without evicting from OS page cache
body: <p>(This is intended primary for Linux, or ideally any POSIX system.)</p>
  
  <p>I'm looking for a way of reading a large number of files (any one of which might be up to 1GB by itself) with the following characteristics, as I read the pages in:</p>
  
  <ul>
  <li>If the relevant disk page is already in the file system cache, that one is used.</li>
  <li>If the relevant page isn't in the disk cache, it's fetched from disk but any existing cached disk pages are not evicted.</li>
  </ul>
  
  <p>The idea is to be able to read all of these files without polluting the disk cache or evicting the current working set.</p>
  
  <p>Any guidance?</p>