On Thu, Mar 14, 2013 at 03:56:33PM -0700, "Martin v. Löwis" wrote:
> Am 14.03.13 11:23, schrieb Trent Nelson:
> > Porting the Py_PXCTX part is trivial compared to the work that is
> > going to be required to get this stuff working on POSIX where none
> > of the sublime Windows concurrency, synchronisation and async IO
> > primitives exist.
>
> I couldn't understand from your presentation why this is essential
> to your approach. IIUC, you are "just" relying on the OS providing
> a thread pool, (and the sublime concurrency and synchronization
> routines are nothing more than that, ISTM).
Right, there's nothing Windows* does that can't be achieved on
Linux/BSD, it'll just take more scaffolding (i.e. we'll need to
manage our own thread pool at the very least).
[*]: actually, the interlocked singly-linked list stuff concerns me;
the API seems straightforward enough but the implementation becomes
deceptively complex once you factor in the ABA problem. (I'm not
aware of a portable open source alternative for that stuff.)
> Implementing a thread pool on top of select/poll/kqueue seems
> straight-forward.
Nod, that's exactly what I've got in mind. Spin up a bunch of
threads that sit there and call poll/kqueue in an endless loop.
That'll work just fine for Linux/BSD/OSX.
Actually, what's really interesting is the new registered IO
facilities in Windows 8/2012. The Microsoft recommendation for
achieving the ultimate performance (least amount of jitter, lowest
latency, highest throughput) is to do something like this:
while (1) {
if (!DequeueCompletionRequests(...)) {
YieldProcessor();
continue;
} else {
/* Handle requests */
}
}
That pattern looks a lot more like what you'd do on Linux/BSD (spin
up a thread per CPU and call epoll/kqueue endlessly) than any of the
previous Windows IO patterns.
Trent.
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