Messages in this thread | | | Subject | Re: PATCH: Raw device IO for 2.1.131 | From | Jes Sorensen <> | Date | 14 Dec 1998 14:06:08 +0100 |
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>>>>> "Richard" == Richard Gooch <rgooch@atnf.csiro.au> writes:
Richard> Jes Sorensen writes: >> SGI managed to get zero copy right for write() on a socket and it >> works great, I'd love having Linux do the same.
Richard> To get you what you want without resorting to sendfile(), Richard> we'd have to be able to be able to pin down user pages and Richard> then initiate DMA. Linus has said he doesn't like that idea Richard> and has also pointed out he feels that the copy operation Richard> would not be a significant overhead. Other have mentioned Richard> other applications (video capture and processing) where they Richard> feel an extra copy *is* significant. But is this the case Richard> with your application? It seems to me that if you have a Richard> bunch of user pages you want to DMA out, you have already Richard> spent a considerable amount of time generating the data, so Richard> an extra copy is not significant. Is that so?
No most of our applications do read(filefd), write(sockfd) and as such it could probably be done with sendfile, the main issue is that it requires rewriting the code as a special case for Linux.
Jes
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