waiting on sbwait

[Danny Braniss]

> Danny Braniss wrote:
> 
> >Hi,
> >	We have a host running samba under -stable 4.10, and quiet frequently
> >it becomes uresponsive, hitting ^T gives 
> >
> >load: 0.00  cmd: ls 12807 [sbwait] 0.00u 0.00s 0% 160k
> >
> >so my guess is that we are running out of some resource (socket buffer).
> >
> >so, if this is true, is there some sysctl to increase?
> >
> >danny

> I'm not sure if it's what you're hitting, but Perhaps the sysctl 
> "kern.ipc.maxsockets" needs to be raised, though it seems like you'd 
> need a decent amount of concurrent active sessions to reach this 
> ceiling. Also it's read-only, so you'll want to tune it in loader.conf.
> 
> -mpf
> 

sometimes we get 
load: 0.04  cmd: dmesg 13453 [nfsrcvlk] 0.00u 0.00s 0% 148k

and looking through the code, there might be some connection between sbwait
and nfsrcvlk, but i doubt that it's sockets that im running out off, neither
mbufs, since:

foundation> netstat -m
326/1216/26624 mbufs in use (current/peak/max):
        326 mbufs allocated to data
321/428/6656 mbuf clusters in use (current/peak/max)
1160 Kbytes allocated to network (5% of mb_map in use)
0 requests for memory denied
0 requests for memory delayed
0 calls to protocol drain routines

also, the process enters sbwait either in sosend or soreceive, make me
believe that it's some resource, rather than data, that is missing.

the fact that this 'unresponsivness' happens sometimes is making this
rather challenging, but try to tell this to the users :-)

danny