----- Original Message ----- > On 06/26/2018 10:40 AM, David Wysochanski wrote: > > On Tue, 2018-06-26 at 11:27 -0400, Dave Anderson wrote: > >> > >> ----- Original Message ----- > >>> On Tue, 2018-06-26 at 15:34 +0100, Jeremy Harris wrote: > >>>> On 06/26/2018 03:29 PM, David Wysochanski wrote: > >>>>> On Tue, 2018-06-26 at 09:21 -0400, Dave Anderson wrote: > >>>>>> Yes, by default all list entries encountered are put in the built-in > >>>>>> hash queue, specifically for the purpose of determining whether there > >>>>>> are duplicate entries. So if it's still running, it hasn't found any. > >>>>>> > >>>>>> To avoid the use of the hashing feature, try entering "set hash off" > >>>>>> before kicking off the command. But of course if it finds any, it > >>>>>> will loop forever. > >>>>>> > >>>>> > >>>>> Ah ok yeah I forgot about the built-in list loop detection! > >>>> > >>>> For a storage-less method of list loop-detection: run two walkers > >>>> down the list, advancing two versus one elements. If you ever > >>>> match the same element location after starting, you have a loop. > >>> > >>> I agree some algorithm [1] without a hash table may be better > >>> especially for larger lists. > >> > >> I'll await your patch... > >> > > > > Do you see any advantage to keeping the hash table for loop detection > > or would you accept a patch that removes it completely in favor of a > > another algorithm? > > Could the same algorithm be modified so that it can slow down after a > certain number of list members, say maybe saving only every 10th element > to the hash (but checking every new one)? I've seen list corruption where a list containing hundreds of entries contains an entry that points back to another entry in the list that came hundreds of entries before it. Dave -- Crash-utility mailing list Crash-utility@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/crash-utility
