On Fri, 6 Jan 2012 09:54:46 -0800, Mike Waychison <mikew@xxxxxxxxxx> wrote: > On Wed, Jan 4, 2012 at 6:46 PM, Mike Waychison <mikew@xxxxxxxxxx> wrote: > > On Wed, Jan 4, 2012 at 4:31 PM, Rusty Russell <rusty@xxxxxxxxxxxxxxx> wrote: > >> 4) You use the skb data for the linked list; use the skb head's list. > > What did you mean by this? I was under the impression that the ->next > and ->prev fields in sk_buff were the first two elements specifically > so that the pointer could be treated as a list_head. If it's the cast > in particular that you have an objection with, I can easily change > this to a singly linked list threaded through ->next if that's > cleaner. Yep, I saw the cast and misread your code. I could have sworn that skb used a real list_head these days, but I'm wrong. > >> > >> Instead, here's how I think it should be done: > ... > > > > This sounds reasonable to me. I'll see what I can muster together this week. > > > > So I started implementing it the way you were mentioning, and ran into > a problem with the original patchset. > > Currently the "mergeable" and "big" receive buffers use a private page > free list (virtnet_info->pages) which has no synchronization itself. > This means that the batched version can't use get_a_page() and > give_pages() as is, which reduces the need to re-use the same alloc > halves that I've split. Alternatives I can think of at this point: > > - pass in a flag to the allocators like "bool is_serial" that is true > if we are serializing with napi, (which determines if we can much with > vi->pages) > or > - not use the same allocators for the "mergeable" and "big" paths. > The mergeable allocator in the non-serialized case reduces to > alloc_page(), while the big allocator looks like a copy and paste that > uses alloc_page instead of get_a_page(). > > Preferences? I'll code one of the two up and see what it looks like. Whatever results in a cleaner driver, I'm happy. Thanks, Rusty. _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
