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docs: net: fix inaccuracies in msg_zerocopy.rst 

Replace "sendpage" with "sendfile". Remove comment about
ENOBUFS when the sockopt hasn't been set; experimentation
indicates that this is not true.

Signed-off-by: nick black <dankamongmen@gmail.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/r/Y/gg/EhIIjugLdd3@schwarzgerat.orthanc
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
nick black 2023-02-23 21:29:16 -05:00 committed by Jakub Kicinski
parent 766d1bdceb
commit bce9045993
1 changed files with 3 additions and 3 deletions
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6
Documentation/networking/msg_zerocopy.rst
View File

@ -15,7 +15,7 @@ Opportunity and Caveats
Copying large buffers between user process and kernel can be Copying large buffers between user process and kernel can be
expensive. Linux supports various interfaces that eschew copying, 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. underlying copy avoidance mechanism to common socket send calls.
Copy avoidance is not a free lunch. As implemented, with page pinning, Copy avoidance is not a free lunch. As implemented, with page pinning,
@ -83,8 +83,8 @@ Pass the new flag.
ret = send(fd, buf, sizeof(buf), MSG_ZEROCOPY); ret = send(fd, buf, sizeof(buf), MSG_ZEROCOPY);
A zerocopy failure will return -1 with errno ENOBUFS. This happens if 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 socket exceeds its optmem limit or the user exceeds their ulimit on
the user exceeds its ulimit on locked pages. locked pages.
Mixing copy avoidance and copying Mixing copy avoidance and copying