[openib-general] Re: OpenIB Thread Usage

[Michael S. Tsirkin]

Hello!
Quoting r. Sean Hefty (mshefty at ichips.intel.com) "Re: [openib-general] Re: OpenIB Thread Usage":
> Roland Dreier wrote:
> 
> >    Sean> I thought about this approach, but wasn't sure about taking
> >    Sean> a context switch.  I guess with QP redirection, this
> >    Sean> wouldn't be an issue though.
> >
> >I don't think there's a choice.  If the CM processes MADs from one queue
> >and time wait expirations from another, it's not possible to prevent
> >the MAD queue from getting arbitrarily far ahead of the time wait
> >queue.  This results in QPs never being reaped and eventually the
> >system runs out of memory.
> 
> I'm not understanding the issue here.  If connections are being made 
> faster than QPs are leaving the time wait state, then the system will 
> eventually run out of resources.  But this problem seems somewhat 
> separate from the threading model used to establish connections, unless 
> that thread is preventing other threads from executing.

The idea I think was that if you start dropping MADs when you can
not establish a connection, the remote side will retry.
One way to drop MADs is by blocking the MAD work thread.

MST