Messages in this thread | | | Date | Wed, 30 May 2007 22:46:51 +0200 | From | Eric Dumazet <> | Subject | Re: Syslets, Threadlets, generic AIO support, v6 |
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Linus Torvalds a écrit : > > On Wed, 30 May 2007, Eric Dumazet wrote: >> So yes, reimplement sendfile() should help to find last splice() bugs, and as >> a bonus it could add non blocking disk io, (O_NONBLOCK on input file -> >> socket) > > Well, to get those kinds of advantages, you'd have to use splice directly, > since sendfile() hasn't supported nonblocking disk IO, and the interface > doesn't really allow for it.
sendfile() interface doesnt allow it, but if you open("somediskfile", O_RDONLY | O_NONBLOCK), then splice() based sendfile() can perform a non blocking disk io, (while starting an io with readahead)
I actually use this trick myself :)
(splice(disk -> pipe, NONBLOCK), splice(pipe -> worker))
non blocking disk io, + zero copy :)
> > In fact, since nonblocking accesses require also some *polling* method, > and we don't have that for files, I suspect the best option for those > things is to simply mix AIO and splice(). AIO tends to be the right thing > for disk waits (read: short, often cached), and if we can improve AIO > performance for the cached accesses (which is exactly what the threadlets > should hopefully allow us to do), I would seriously suggest going that > route. > > But the pure "use splice to _implement_ sendfile()" thing is worth doing > for all the other reasons, even if nonblocking file access is not likely > one of them. > > Linus > >
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