| Message ID | 167361788585.531803.686364041841425360.stgit@firesoul (mailing list archive) |
|---|---|
| Headers | show |
| Series | net: use kmem_cache_free_bulk in kfree_skb_list | expand |
Hello: This series was applied to netdev/net-next.git (master) by Paolo Abeni <pabeni@redhat.com>: On Fri, 13 Jan 2023 14:51:54 +0100 you wrote: > The kfree_skb_list function walks SKB (via skb->next) and frees them > individually to the SLUB/SLAB allocator (kmem_cache). It is more > efficient to bulk free them via the kmem_cache_free_bulk API. > > Netstack NAPI fastpath already uses kmem_cache bulk alloc and free > APIs for SKBs. > > [...] Here is the summary with links: - [net-next,V2,1/2] net: fix call location in kfree_skb_list_reason https://git.kernel.org/netdev/net-next/c/a4650da2a2d6 - [net-next,V2,2/2] net: kfree_skb_list use kmem_cache_free_bulk https://git.kernel.org/netdev/net-next/c/eedade12f4cb You are awesome, thank you!
The kfree_skb_list function walks SKB (via skb->next) and frees them individually to the SLUB/SLAB allocator (kmem_cache). It is more efficient to bulk free them via the kmem_cache_free_bulk API. Netstack NAPI fastpath already uses kmem_cache bulk alloc and free APIs for SKBs. The kfree_skb_list call got an interesting optimization in commit 520ac30f4551 ("net_sched: drop packets after root qdisc lock is released") that can create a list of SKBs "to_free" e.g. when qdisc enqueue fails or deliberately chooses to drop . It isn't a normal data fastpath, but the situation will likely occur when system/qdisc are under heavy workloads, thus it makes sense to use a faster API for freeing the SKBs. E.g. the (often distro default) qdisc fq_codel will drop batches of packets from fattest elephant flow, default capped at 64 packets (but adjustable via tc argument drop_batch). Performance measurements done in [1]: [1] https://github.com/xdp-project/xdp-project/blob/master/areas/mem/kfree_skb_list01.org --- Jesper Dangaard Brouer (2): net: fix call location in kfree_skb_list_reason net: kfree_skb_list use kmem_cache_free_bulk net/core/skbuff.c | 68 +++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 57 insertions(+), 11 deletions(-) --