Messages in this thread | | | Date | Wed, 10 Jan 2001 02:19:20 +0100 (CET) | From | Ingo Molnar <> | Subject | Re: [PLEASE-TESTME] Zerocopy networking patch, 2.4.0-1 |
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On Tue, 9 Jan 2001, Dave Zarzycki wrote:
> In user space, how do you know when its safe to reuse the buffer that > was handed to sendmsg() with the MSG_NOCOPY flag? Or does sendmsg() > with that flag block until the buffer isn't needed by the kernel any > more? If it does block, doesn't that defeat the use of non-blocking > I/O?
sendmsg() marks those pages COW and copies the original page into a new one for further usage. (the old page is used until the packet is released.) So for maximum performance user-space should not reuse such buffers immediately.
Ingo
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