Re: [PATCH][RFC] relayfs (1/4) (Documentation)

From: Hubertus Franke
Date: Thu Nov 13 2003 - 09:21:10 EST


David S. Miller wrote:
On Tue, 14 Oct 2003 11:32:28 +0000
Richard J Moore <rasman@xxxxxxxxxx> wrote:


Interesting, that assumes sequential processing, if not semi-synchronous processing of events on the receiver side, which is far from guaranteed when considering low-level tracing especially for flight-recorder applications.


With netlink you may receive the data asynchronously however you
wish after you've requested a dump.

I would like to ask that you go study how netlink works and is used
by things like routing daemons before we discuss this further as
it looks to me like half the conversation is going to be showing
you how netlink works. And hey there's even an RFC on netlink :)
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Dave, is there a short write-up (2-3 pages) about netlink.
I like to get a quick understanding about it and how it measures
up to relayfs or vice versa. From some of the discussions here I get
the feeling that they simply might address orthogonal issues.

I recently started using relayfs for various projects after hearing
about it at OLS'03. I often need to get information out of the kernel
(either debugging in interrupt/scheduling context thus preempting use
of printk) or other information for data recording (call it trace or whatever).
I don't want to use existing "media" (e.g. syslog) as it either clobbers up that media or I have to search for the information I have put in or the format (typically char) is not appropriate for my use. I simply want a dedicated channel to get to the data in the format that I select.

I found relayfs extremely easy to use. Channel setup is a breeze.
User level consumption is through file operations. IMHO it just simply
can not get any simpler that this....
It works in interrupt/scheduling context. Has extremely low overhead
and is stable. I really would like to see relayfs be picked up.
Its a loadable filesystem that at least to this user has provided
some real value, so why would inclusion be so difficult/objectable.

You providing a short document might help me get an appreciation for
your argument.

-- Hubertus

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