On Thu, Oct 20, 2005 at 10:51:00AM +0200, Ragnar Lonn wrote: > Gleb Smirnoff wrote: > > >Although the memory overhead is not noticable on modern i386 and amd64 > >PCs I don't think that we should waste so much memory. We should keep > >in mind the existence of embedded architectures with little memory. > > > >In most cases people use 10 - 30 VLANs. I suggest to use a hash, like it > >is already done in ng_vlan(4). This hash makes every sixteenth VLAN to fall > >into same slot. Since most people allocate VLAN ids contiguously the hash > >distribution should be good. > > > >Moreover, I suggest Yar and Ruslan to work together and make the hash code > >shared between vlan(4) and ng_vlan(4), not copy-and-pasted. > > It looks as if ng_vlan implements a standard hash. Wouldn't a hashtree > be a good > compromise between speed and memory usage? Of course, a 16-slot hash is > a lot > better than no hash at all :-)
The only problem with the hash currently used in ng_vlan is that it is fixed-width. I think it will be easy to teach it how to cope with variable bit-width of hash using the same xor-folding technique. I hope I'll have free time this week-end to test the performance of the approaches discussed since implementing them is no problem at all. -- Yar _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "[EMAIL PROTECTED]"
