Re: [RFC][PATCH 0/5] relayfs

Gianni Tedesco
2003-07-15T16:25:40Z

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On Tue, 2003-07-15 at 17:01, Tom Zanussi wrote:
> Gianni Tedesco writes:
> > On Tue, 2003-07-15 at 16:15, Tom Zanussi wrote:
> > > The following 5 patches implement relayfs, adding a dynamic channel
> > > resizing capability to the previously posted version.
> > >
> > > relayfs is a filesystem designed to provide an efficient mechanism for
> > > tools and facilities to relay large amounts of data from kernel space
> > > to user space. Full details can be found in Documentation/filesystems/
> > > relayfs.txt. The current version can always be found at
> > > http://www.opersys.com/relayfs.
> >
> > Could this be used to replace mmap() packet socket, how does it compare?
>
> I think so - you could send high volumes of packet traffic to a bulk
> relayfs channel and read it from the mmap'ed relayfs file in user
> space. The Linux Trace Toolkit does the same thing with large volumes
> of trace data - you could look at that code as an example
> (http://www.opersys.com/relayfs/ltt-on-relayfs.html).

What are the semantics of the mmap'ing the buffer? With mmaped packet
socket the userspace (read-side) requires no sys-calls apart from when
the buffer is empty, it then uses poll(2) to sleep until something new
is put in the buffer. Can relayfs do a similar thing? poll is not
mentioned in the docs...

Thanks.

--
// Gianni Tedesco (gianni at scaramanga dot co dot uk)
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