On 2/4/21 10:05 AM, Jesper Dangaard Brouer wrote: [...]
It was Andrew (AKPM) that wanted the API to either return the requested number of objects or fail. I respected the MM-maintainers request at that point, even-though I wanted the other API as there is a small performance advantage (not crossing page boundary in SLUB). At that time we discussed it on MM-list, and I see his/the point: If API can allocate less objs than requested, then think about how this complicated the surrounding code. E.g. in this specific code we already have VETH_XDP_BATCH(16) xdp_frame objects, which we need to get 16 SKB objects for. What should the code do if it cannot get 16 SKBs(?).
Right, I mentioned the error handling complications above wrt < n_skb case. I think iff this ever gets implemented and there's a need, it would probably be best to add a new flag like __GFP_BULK_BEST_EFFORT to indicate that it would be okay to return x elements with x being in (0, size], so that only those callers need to deal with this, and all others can expect [as today] that != 0 means all #size elements were bulk alloc'ed. Thanks, Daniel
