High interrupt rate on a PF box + performance

[Damien Fleuriot]

On 1/27/11 9:58 PM, Jeremy Chadwick wrote:
> 
> Kernel folks should be able to talk about this in detail, but my
> understanding is that the kernel itself supports multiple threads, but
> the question is whether or not the drivers or relevant "pieces" (e.g.
> igb(4) driver, pf, TCP stack, etc.) support SMP (multi-core/threading)
> or not.  I think this is referred to as something being "MPSAFE" or not.
> 
> The things you see during boot -- [ITHREAD], [FILTER], and
> [GIANT-LOCKED] play a role as well, but I think those indicate what
> style of locking is used (since some drivers/features might not work
> properly in a multiprocessor environment).
> 
> I'm trying to avoid correlating "multiprocessor safe" with "makes use of
> multiple processors".  I'm an old 65xxx CPU guy, this SMP stuff is still
> "new technology" to me when it comes to actual operations/mechanics.
> 
> Regarding TCP and SMP, this is regularly touched on in the FreeBSD
> Status Reports that go out (always worth reading).  See "TCP SMP
> scalability project":
> 
> http://www.freebsd.org/news/status/report-2010-10-2010-12.html
> 
> I know all this information is technical of course and doesn't answer
> your question directly.  I wish there was something more authoritative
> when it came to this question.
> 



Thanks for your time explaining all this, I'll have a look at your
link, even if it may or may not apply directly to our case, it'll still
be interesting material.


I'll have to poke around for information about the kernel and how it
works with multithreading :)