On Mon, Nov 11, 2024 at 07:01:26PM -0800, Alexei Starovoitov wrote: > On Mon, Nov 11, 2024 at 6:15 AM Hou Tao <houtao@xxxxxxxxxxxxxxx> wrote: > > > > > > > > On 11/10/2024 7:29 PM, Florian Lehner wrote: > > > Introduce a new flag for batch operations that allows the deletion process > > > to continue even if certain keys are missing. This simplifies map flushing > > > by eliminating the requirement to maintain a separate list of keys and > > > makes sure maps can be flushed with a single batch delete operation. > > > > Is it expensive to close and recreate a new map instead ? If it is > > expensive, does it make more sense to add a new command to delete all > > elements in the map ? Because reusing the deletion logic will make each > > deletion involve an unnecessary lookup operation. > > +1 to above questions. There is an eBPF map, that a variable number of eBPF programs use, to access common states for a variable number of connections. On predefined events, a set of keys is deleted from this map. This set can either be all keys or just a subset of all keys - but it is not guaranteed that this set of keys still exists in this eBPF map. The current work around is to use bpf_map_lookup_and_delete_batch(), as this operation continues on missing keys and clears all requested keys from the eBPF map. The noticeable downside of bpf_map_lookup_and_delete_batch() is the memory requirement that comes with the lookup and allocation for the values. > > [..] If it is > > expensive, does it make more sense to add a new command to delete all > > elements in the map ? It felt like bpf_map_delete_batch() was introduced for this use case. So adding a new command was not considered. > > In addition: > > What is the use case ? > Are you trying to erase all elements from the map ? > > If so you bpf_for_each_map_elem() and delete elems while iterating. bpf_for_each_map_elem() could be an option if the map should be flushed completley, but in most cases only a subset of keys should be removed from the map. > > This extra flag looks too specific. Sure, the proposed flag is focused on the delete operation. What could be the requirement to make it less specific? > > pw-bot: cr
