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The tricky part...

Posted Apr 27, 2006 16:33 UTC (Thu) by axboe (subscriber, #904)
In reply to: How does this differ from aio_write? by kingdon
Parent article: The splice() weekly news

isn't so much how to notify reusability, but rather when to determine the safety of doing so. We still need to change a bit of infrastructure for this - eg, get rid of ->sendpage() and actually pass the pipe_inode_info down for network transmit and only have it do the ->release on the buffers when they have been sent out. The issue right now is that the ->release is done as soon as we pass the page to the network stack, which is too soon of course.

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What does vmsplice() add?

Posted Apr 28, 2006 2:17 UTC (Fri) by xoddam (subscriber, #2322) [Link]

Determining completion is indeed tricky, especially where remote hosts
are involved. But there are already two good choices for the interface:
write() blocks until the buffer may be reused by the application,
aio_write() instead posts a notification. What does vmsplice() add?

(Changing to a vector operation changes the names of the functions, but
not the nature of the question).

What does vmsplice() add?

Posted Apr 28, 2006 4:21 UTC (Fri) by axboe (subscriber, #904) [Link]

Blocking on the next vmsplice comes automatically, since you can't replace buffers that haven't been ->release'd yet. So that's how it already works. As I said, the missing bit is getting the release right.