On Tue, Dec 19, 2017 at 11:56:30AM -0800, Rao Shoaib wrote: > On 12/19/2017 11:30 AM, Matthew Wilcox wrote: > >On Tue, Dec 19, 2017 at 09:52:27AM -0800, rao.shoaib@xxxxxxxxxx wrote: [ . . . ] > >I've been doing a lot of thinking about this because I really want a > >way to kfree_rcu() an object without embedding a struct rcu_head in it. > >But I see no way to do that today; even if we have an external memory > >allocation to point to the object to be freed, we have to keep track of > >the grace periods. > I am not sure I understand. If you had external memory you can > easily do that. > I am exactly doing that, the only reason the RCU structure is needed > is to get the pointer to the object being freed. This can be done as long as you are willing to either: 1. Occasionally have kfree_rcu() wait for a grace period. 2. Occasionally have kfree_rcu() allocate memory. 3. Keep the rcu_head, but use it only when you would otherwise have to accept the above two penalties. (The point of this is that tracking lists of memory waiting for a grace period using dense arrays improves cache locality.) There might be others, and if you come up with one, please don't keep it a secret. The C++ standards committee insisted on an interface using option #2 above. (There is also an option to use their equivalent of an rcu_head.) Thanx, Paul -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
