Re: ice-broker scan thread

[David Boreham <david_list(at)boreham(dot)org>]

Qingqing Zhou wrote:

On Mon, 28 Nov 2005, Gavin Sherry wrote:
  

MySQL, Oracle and others implement read-ahead threads to simulate async IO
'pre-fetching'.
    

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 ...
  

I don't think your NT overlapped I/O code is quite right. At least
I think it will issue reads at a high rate without waiting for any of them
to complete. Beyond some point that has to give the kernel gut-rot.
But anyway, I wouldn't expect the use of aio to make any
significant difference in an already threaded test program.
The point of aio is to allow
I/O concurrency _without_ the use of threads or multiple processes.
You could re-write your program to have a single thread but use aio.
In that case it should show the same read ahead benefit that you see
with the thread.