Messages in this thread | | | Date | Thu, 16 Nov 2006 22:21:07 +0100 | From | Jens Axboe <> | Subject | Re: splice/vmsplice performance test results |
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On Thu, Nov 16 2006, David Miller wrote: > From: "Jim Schutt" <jaschut@sandia.gov> > Date: Thu, 16 Nov 2006 11:08:59 -0700 > > > Or is read+write really the fastest way to get data off a > > socket and into a file? > > There is still no explicit TCP support for splice/vmsplice so things > get copied around and most of the other advantaves of splice/vmplice > aren't obtained either. So perhaps that explains your numbers.
There should not be any copying for tcp send, at least no more than what sendfile() did/does. Hmm?
> Jens Axboe tries to get things working, and others have looked into it > too, but adding TCP support is hard and for several reasons folks like > Alexey Kuznetsov and Evgeniy Polyakov believe that sys_receivefile() > is an interface much better suited for TCP receive. > > splice/vmsplice has a lot of state connected to a transaction, and > perhaps that is part of why Evgeniy and Alexey have trouble wrapping > their brains around an efficient implementation.
I hope to try and see if I can help get some of that done, however I need all the help I can get on the networking side. Not sure I understand why it has to be so difficult, if we need to define a wrapper container instead of passing down a pipe that is completely fine with me. The networking code basically just needs to hang on to the pipe_buffer and release it on ack for send, receive is somewhat more involved (and I don't know enough about networking to voice any half-intelligent opinion on that!).
I would just consider it a damn shame if we cannot complete the splice family and need to punt to something else for net receive.
-- Jens Axboe
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