Reg: Route Cache hash key in Linux Network Code

["Pranjal Kumar Dutta" <pranjalkumardutta@xxxxxxxxx>]

 

Hi All,

                    Can anybody explain me the following hash ket generation used in route cache lookup (route.c). I am not able to correlate on what basis from saddr, daddr and ip tos this hash key is generated to minimize bucket collisions. Again the rt_hash_rnd and rt_hash_mask are values decided at system init time from number of physical pages.

 

 static unsigned int rt_hash_code(u32 daddr, u32 saddr, u8 tos)
214 {
215         return ( jhash_3words(daddr, saddr, (u32) tos, rt_hash_rnd)
216                 & rt_hash_mask);
217 }
218
 

                      Any clarification on this pieceof code would be of great help.

 

Thanks in advance,

Pranjal