Identify and eliminate expensive operations in frequently executed code paths, particularly in packet processing and network handling contexts. Hot paths are code sections that execute repeatedly at high frequency, where even small performance penalties can significantly impact overall system performance.
Common expensive operations to avoid in hot paths include:
Instead, use performance-optimized alternatives:
Example from eBPF packet processing:
// Avoid: expensive lookup per packet
sk = bpf_skc_lookup_tcp(skb, tuple, tuple_len, BPF_F_CURRENT_NETNS, 0);
// Better: use map-based lookup
struct connection_info *conn = map_lookup_elem(&connection_map, &key);
// Avoid: debug logging in production hot path
#ifdef DEBUG_MODE
printk("Processing packet from %pI4\n", &iph->saddr);
#endif
Profile and measure hot paths to identify bottlenecks, then prioritize optimizing the most frequently executed expensive operations first.
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