Qingqing Zhou wrote: <blockquote cite="midPine.LNX.4.58.0511282350370.13833@josh.db" type="cite"><pre wrap="">
On Mon, 28 Nov 2005, Gavin Sherry wrote: </pre><blockquote type="cite"><pre wrap="">MySQL, Oracle and others implement
read-aheadthreads to simulate async IO
'pre-fetching'. </pre></blockquote><pre wrap="">
Due to my tests on Windows (using the attached program and change
enable_aio=true), seems aio doesn't help as a separate thread - but maybe
because my usage is wrong ... </pre></blockquote> I don't think your NT overlapped I/O code is quite right. At least<br
/>I think it will issue reads at a high rate without waiting for any of them<br /> to complete. Beyond some point that
hasto give the kernel gut-rot.<br /> But anyway, I wouldn't expect the use of aio to make any<br /> significant
differencein an already threaded test program. <br /> The point of aio is to allow<br /> I/O concurrency _without_ the
useof threads or multiple processes.<br /> You could re-write your program to have a single thread but use aio.<br />
Inthat case it should show the same read ahead benefit that you see<br /> with the thread.<br /><br /><br /><br />
