Liangxu Linux
Sep 4, 2024 · Fundamentals
Why Does TCP Send‑Q Exceed SO_SNDBUF? Inside Linux Kernel Buffer Mechanics
A Linux client sets SO_SNDBUF to 4096 bytes, sends 1 KB packets while the server never reads, yet the TCP Send‑Q grows to 14480 bytes because the kernel doubles the buffer size, adds overhead, and expands memory via GSO and sk_wmem scheduling.
GSOLinux kernelSO_SNDBUF
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