From: Steven Rostedt <srostedt@redhat.com>
To: 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>,
Frederic Weisbecker <fweisbec@gmail.com>
Subject: Re: Warning from ring buffer code (Was: Re: linux-next: tip tree build warning)
Date: Mon, 14 Sep 2009 14:31:16 -0400 [thread overview]
Message-ID: <1252953076.2964.156.camel@localhost.localdomain> (raw)
In-Reply-To: <1252952621.31964.0.camel@twins>
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
next prev parent reply other threads:[~2009-09-14 18:32 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-08-04 6:16 linux-next: tip tree build warning Stephen Rothwell
2009-08-04 16:24 ` Steven Rostedt
2009-09-12 6:53 ` Warning from ring buffer code (Was: Re: linux-next: tip tree build warning) Stephen Rothwell
2009-09-12 7:39 ` Ingo Molnar
2009-09-12 10:46 ` Stephen Rothwell
2009-09-12 11:12 ` Jaswinder Singh Rajput
2009-09-14 15:16 ` 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 [this message]
2009-09-14 18:41 ` Frederic Weisbecker
2009-09-15 7:16 ` Peter Zijlstra
2009-09-15 9:01 ` Frédéric Weisbecker
2009-09-14 18:38 ` Frederic Weisbecker
2009-09-14 13:50 ` Steven Rostedt
2009-09-14 13:53 ` Ingo Molnar
2009-09-14 22:36 ` Stephen Rothwell
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