Copying large buffers between user process and kernel can be
expensive. Linux supports various interfaces that eschew copying,
-such as sendpage and splice. The MSG_ZEROCOPY flag extends the
+such as sendfile and splice. The MSG_ZEROCOPY flag extends the
underlying copy avoidance mechanism to common socket send calls.
Copy avoidance is not a free lunch. As implemented, with page pinning,
ret = send(fd, buf, sizeof(buf), MSG_ZEROCOPY);
A zerocopy failure will return -1 with errno ENOBUFS. This happens if
-the socket option was not set, the socket exceeds its optmem limit or
-the user exceeds its ulimit on locked pages.
+the socket exceeds its optmem limit or the user exceeds their ulimit on
+locked pages.
Mixing copy avoidance and copying