From: Frederic Weisbecker <fweisbec@gmail.com>
To: Steven Rostedt <srostedt@redhat.com>,
Peter Zijlstra <peterz@infradead.org>
Cc: Christopher Li <sparse@chrisli.org>,
Jaswinder Singh Rajput <jaswinder@kernel.org>,
Ingo Molnar <mingo@elte.hu>,
Stephen Rothwell <sfr@canb.auug.org.au>,
Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>,
linux-next@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-sparse@vger.kernel.org,
Josh Triplett <josh@freedesktop.org>
Subject: Re: Warning from ring buffer code (Was: Re: linux-next: tip tree build warning)
Date: Mon, 14 Sep 2009 20:41:24 +0200 [thread overview]
Message-ID: <20090914184123.GC6045@nowhere> (raw)
In-Reply-To: <1252953076.2964.156.camel@localhost.localdomain>
On Mon, Sep 14, 2009 at 02:31:16PM -0400, Steven Rostedt wrote:
> On Mon, 2009-09-14 at 20:23 +0200, Peter Zijlstra wrote:
> > On Mon, 2009-09-14 at 14:17 -0400, Steven Rostedt wrote:
> > > Frederic, how big can one of those events get. The ring buffer (and
> > > TRACE_EVENT) allow up to almost a page size, which is very hefty for the
> > > stack. This code needs to either be rewritten or we need to set a limit
> > > to the size of a profile entry.
> >
> > Yeah, that needs to get a re-write.. I've complained about this when it
> > went in.
>
> One answer is to create a per cpu buffer that is big enough to hold the
> data needed. Then you can disable interrupts an use it without worry.
>
> If you need to also handle NMIs, then create a per_cpu NMI buffer too,
> and use that if "in_nmi()" is true.
>
> -- Steve
Looks like a nice idea.
Peter, does that sound acceptable to you to disable interrupts during a
profiled tracepoint event?
next prev parent reply other threads:[~2009-09-14 18:41 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20090804161640.70817ee6.sfr@canb.auug.org.au>
[not found] ` <1249403089.4634.139.camel@localhost.localdomain>
[not found] ` <20090912165300.9d257283.sfr@canb.auug.org.au>
[not found] ` <20090912073906.GA3972@elte.hu>
[not found] ` <1252753957.12217.10.camel@ht.satnam>
2009-09-14 15:16 ` Warning from ring buffer code (Was: Re: linux-next: tip tree build warning) Steven Rostedt
2009-09-14 17:09 ` Christopher Li
2009-09-14 18:17 ` Steven Rostedt
2009-09-14 18:23 ` Peter Zijlstra
2009-09-14 18:31 ` Steven Rostedt
2009-09-14 18:41 ` Frederic Weisbecker [this message]
2009-09-15 7:16 ` Peter Zijlstra
2009-09-15 9:01 ` Frédéric Weisbecker
2009-09-14 18:38 ` Frederic Weisbecker
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