Date: Thu, 15 Dec 2005 04:33:54 +0100
From: Andi Kleen <ak@suse.de>
To: Martin Peschke <mp3@de.ibm.com>
Cc: Andi Kleen <ak@suse.de>, akpm@osdl.org, linux-kernel@vger.kernel.org
Subject: Re: [patch 1/6] statistics infrastructure - prerequisite: scatter-gather ringbuffer
Message-ID: <20051215033354.GR23384@wotan.suse.de>
References: <43A044AA.4040103@de.ibm.com> <p73d5jz8r7n.fsf@verdi.suse.de> <43A0D68D.8090405@de.ibm.com>
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> Relayfs seems to be the right thing to convey streams of incremental 
> pieces of data, like trace records as implemented by 
> arch/s390/kernel/debug.c, for example. Relayfs would work for statistics 
> that involve data growth like a history of a counter, for example, or 
> the raw measurement data reported for statistic updates. I doubt it is 
> the right thing for counters, fill level indicators and histograms; 

For those we traditionally use ASCII files if the data is small.
If it's big relayfs is probably the right answer.

> basically for all types of statistics that do not continuously put their 
> hands on untouched memory to store their results.
> 
> I am currently using debugfs, which works fine for all of these cases. 
> In addition, I need some ringbuffer functionality, though.

IIRC relayfs was changed to be able to handle files in debuggfs by
just plugging in the file operations.

-Andi
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