On 08/25/2012 06:24 AM, Mathieu Desnoyers wrote: > * Tejun Heo (tj@xxxxxxxxxx) wrote: >> Hello, >> >> On Sat, Aug 25, 2012 at 12:59:25AM +0200, Sasha Levin wrote: >>> Thats the thing, the amount of things of things you can do with a given bucket >>> is very limited. You can't add entries to any point besides the head (without >>> walking the entire list). >> >> Kinda my point. We already have all the hlist*() interface to deal >> with such cases. Having something which is evidently the trivial >> hlist hashtable and advertises as such in the interface can be >> helpful. I think we need that more than we need anything fancy. >> >> Heh, this is a debate about which one is less insignificant. I can >> see your point. I'd really like to hear what others think on this. >> >> Guys, do we want something which is evidently trivial hlist hashtable >> which can use hlist_*() API directly or do we want something better >> encapsulated? > > My 2 cents, FWIW: I think this specific effort should target a trivially > understandable API and implementation, for use-cases where one would be > tempted to reimplement his own trivial hash table anyway. So here > exposing hlist internals, with which kernel developers are already > familiar, seems like a good approach in my opinion, because hiding stuff > behind new abstraction might make the target users go away. > > Then, as we see the need, we can eventually merge a more elaborate hash > table with poneys and whatnot, but I would expect that the trivial hash > table implementation would still be useful. There are of course very > compelling reasons to use a more featureful hash table: automatic > resize, RT-aware updates, scalable updates, etc... but I see a purpose > for a trivial implementation. Its primary strong points being: > > - it's trivially understandable, so anyone how want to be really sure > they won't end up debugging the hash table instead of their > work-in-progress code can have a full understanding of it, > - it has few dependencies, which makes it easier to understand and > easier to use in some contexts (e.g. early boot). > > So I'm in favor of not overdoing the abstraction for this trivial hash > table, and honestly I would rather prefer that this trivial hash table > stays trivial. A more elaborate hash table should probably come as a > separate API. > > Thanks, > > Mathieu > Alright, let's keep it simple then. I do want to keep the hash_for_each[rcu,safe] family though. -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
