1cface552a
Similar to skb_unref(), add skb_data_unref() to save an expensive atomic operation (and cache line dirtying) when last reference on shinfo->dataref is released. I saw this opportunity on hosts with RAW sockets accidentally bound to UDP protocol, forcing an skb_clone() on all received packets. These RAW sockets had their receive queue full, so all clone packets were immediately dropped. When UDP recvmsg() consumes later the original skb, skb_release_data() is hitting atomic_sub_return() quite badly, because skb->clone has been set permanently. Note that this patch helps TCP TX performance, because TCP stack also use (fast) clones. This means that at least one of the two packets (the main skb or its clone) will no longer have to perform this atomic operation in skb_release_data(). Signed-off-by: Eric Dumazet <edumazet@google.com> Link: https://lore.kernel.org/r/20240307123446.2302230-1-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> |
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