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Date: Thu, 9 Sep 2010 13:29:42 +0200
From: Frederic Weisbecker <fweisbec@gmail.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Harald Gustafsson <hgu1972@gmail.com>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Harald Gustafsson <harald.gustafsson@ericsson.com>,
        Song Yuan <song.yuan@ericsson.com>,
        Steven Rostedt <rostedt@goodmis.org>
Subject: Re: perf events over (net) console?
Message-ID: <20100909112940.GA5267@nowhere>
References: <AANLkTi=yeHyOeewm9tdsHRtj+=d+vE5=NRKGaPyq_yGH@mail.gmail.com> <1284031141.402.1.camel@laptop>
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On Thu, Sep 09, 2010 at 01:19:01PM +0200, Peter Zijlstra wrote:
> On Thu, 2010-09-09 at 13:06 +0200, Harald Gustafsson wrote:
> > Hi,
> > 
> > We would like to monitor the perf events continuously on a remote
> > machine. Does it exist a solution (in the kernel) to direct the output
> > to a console or maybe even a netconsole? We would like to avoid a user
> > space application to transfer it, due to that the machine will be
> > running a test which will heavily load it and we want to avoid as many
> > unrelated user space tasks as possible. If not mainlined does anyone
> > have a patch for this?
> 
> No, and its a daft requirement.
> 
> You need a process context anyway to read the data and send it to
> whatever place you want it.
> 
> Putting that in-kernel serves no purpose what so ever.


But if we bring the splice support, that can be done with minimal userspace
noise. Plus that would work with the usual sockets but not limited to that.

trace-cmd does that to carry the traces over the network.