Re: CVS commit: src/sys/kern

[Mindaugas Rasiukevicius <rmind%netbsd.org@localhost>]

oki%NetBSD.org@localhost wrote:
> In M_WAIT case, m_reclaim() will run and run until get mbuf cluster
> if mclpool limit reached.  If m_reclaim() repeatedly but cannot to
> get new mbuf cluster, m_clget() will not return.
> 
> network stacks using mbufs is use with M_DONTWAIT, but it will failed
> to get new mbuf cluster in this case.  "freeze" means that.

Yes, hitting the limit would trigger m_reclaim() and m_clget() would
block.  It is a quite similar condition to memory or KVA starvation.
However, why such blocking in sosend() is problematic, or, how is it
different from any other WAITOK allocation?

I see the point about the limit.  Inadequately low limit may cause many
blocking processes, while there is still a lot of memory.  However, in
such case, perhaps you want PR_LIMITFAIL, instead of PR_NOWAIT?  Note
that PR_NOWAIT (M_DONTWAIT) has other implications, e.g. it might fail
due to try-locks.  So, I think your fix is incorrect.

Thanks.

-- 
Mindaugas