On Wed, Mar 24, 2021 at 05:30:03PM -0700, Kaz Kylheku wrote: > On 2021-03-24 16:45, Segher Boessenkool wrote: > >On Wed, Mar 24, 2021 at 08:39:10AM -0700, Kaz Kylheku via cfarm-users > >wrote: > >The default is not a restriction, but meant for good performance: > >it is 9216, which is the maximum MTU for any supported network > >interface. > > I understand that sending large UDP packets over the network, > even if IP fragmentation makes that work, is wrongheaded. > > However, the limit also affects local communication over loopback. > > The proof that loopback doesn't have that value as its MTU > is that the datagrams are delivered over loopback when you increase > the limit.
If you want your program to work over loopback only, why don't you use much faster transport methods? > Also: > > kaz@GCC-Farm-MiniMac txr % sysctl -a | grep dgram > net.local.dgram.maxdgram: 2048 > net.local.dgram.recvspace: 4096 > net.inet.udp.maxdgram: 9216 > net.inet.raw.maxdgram: 8192 > > What is "net.local.dgram.maxdgram": is that AF_UNIX? Yes. > Is that also clipped to an even more stringent 2048 for performance, > rather than as a restriction? So that it will fit in one 4k page, presumably. Again, no one cares about datagram performance on loopback, it is a legacy feature. Segher _______________________________________________ cfarm-users mailing list cfarm-users@lists.tetaneutral.net https://lists.tetaneutral.net/listinfo/cfarm-users
