Re: squid, DNS and no buffer space

On Fri, 6 Dec 2024, Michael van Elst wrote:
> On Fri, Dec 06, 2024 at 02:49:03PM +0000, Stephen Borrill wrote:
>> At 13:17 I doubled the values again:
>> 13:17   sysctl -w kern.somaxkva=134217728
>> 13:17   sysctl -w kern.sbmax=134217728
>>
>> The warnings continued:
>
> sbmax is the limit for a single socket buffer.
> somaxkva is the limit for the whole network stack.
>
> If you make the same size, this allows one socket buffer to
> eat all allowed memory. I doubt that this is the problem,
> otherwise you'd need more mbufs allocated to fill the
> larger somaxkva now, but the netstat output didn't change.
>
> But please verify with somaxkva >> sbmax (and a much
> smaller sbmax).

I'm not sure I got that figure from and my recvbuf/sendbuf settings. 
Various posts on the mailing lists, I guess. My local commit message for 
those settings was "TCP tuning to improve scp and rsync-over-ssh 
performance", but I didn't bother giving a reference unfortunately. It 
probably relates to my previous complaints about terrible scp 
performance with a NetBSD ssh server compared to Linux (both with a NetBSD 
ssh client).

Here's what I am currently using after reducing sbmax:

net.inet.tcp.recvbuf_max=16777216
net.inet.tcp.recvbuf_inc=786432
net.inet.tcp.sendbuf_max=16777216
net.inet.tcp.sendbuf_inc=786432
net.inet.tcp.recvspace=262144
net.inet.tcp.sendspace=262144
kern.sbmax=16777216
kern.somaxkva=268435456

There won't be any load until Monday now.

-- 
Stephen