On Wed, 10 Dec 2014 14:22:22 +0000 David Laight <David.Laight@xxxxxxxxxx> wrote: > From: Jesper Dangaard Brouer > > The network stack have some use-cases that puts some extreme demands > > on the memory allocator. One use-case, 10Gbit/s wirespeed at smallest > > packet size[1], requires handling a packet every 67.2 ns (nanosec). > > > > Micro benchmarking[2] the SLUB allocator (with skb size 256bytes > > elements), show "fast-path" instant reuse only costs 19 ns, but a > > closer to network usage pattern show the cost rise to 45 ns. > > > > This patchset introduce a quick mempool (qmempool), which when used > > in-front of the SKB (sk_buff) kmem_cache, saves 12 ns on "fast-path" > > drop in iptables "raw" table, but more importantly saves 40 ns with > > IP-forwarding, which were hitting the slower SLUB use-case. > > > > > > One of the building blocks for achieving this speedup is a cmpxchg > > based Lock-Free queue that supports bulking, named alf_queue for > > Array-based Lock-Free queue. By bulking elements (pointers) from the > > queue, the cost of the cmpxchg (approx 8 ns) is amortized over several > > elements. > > It seems to me that these improvements could be added to the > underlying allocator itself. > Nesting allocators doesn't really seem right to me. Yes, I would very much like to see these ideas integrated into the underlying allocators (hence addressing the mm-list). This patchset demonstrates that it is possible to do something faster than the existing SLUB allocator. Which the network stack have a need for. -- Best regards, Jesper Dangaard Brouer MSc.CS, Sr. Network Kernel Developer at Red Hat Author of http://www.iptv-analyzer.org LinkedIn: http://www.linkedin.com/in/brouer -- 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>