Survey results very helpful, thanks! (was: Re: net.inet.tcp.timer_race: does anyone have a non-zero value?)

On Sun, 7 Mar 2010, Robert Watson wrote:

> If your system shows a non-zero value, please send me a *private e-mail* 
> with the output of that command, plus also the output of "sysctl kern.smp", 
> "uptime", and a brief description of the workload and network interface 
> configuration.  For example: it's a busy 8-core web server with roughly X 
> connections/second, and that has three em network interfaces used to load 
> balance from an upstream source.  IPSEC is used for management purposes (but 
> not bulk traffic), and there's a local MySQL database.

I've now received a number of reports that confirm our suspicion that the race 
does occur, albeit very rarely, and particularly on systems with many cores or 
multiple network interfaces.  Fixing it is definitely on the TODO for 9.0, 
both to improve our ability to do multiple virtual network stacks, but with an 
appropriately scalable fix in mind given our improved TCP scalability for 9.0 
as well.

Thanks for all the responses,

Robert N M Watson
Computer Laboratory
University of Cambridge