From: "Frédéric Weisbecker" <fweisbec@gmail•com>
To: Peter Zijlstra <peterz@infradead•org>
Cc: Steven Rostedt <srostedt@redhat•com>,
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: Tue, 15 Sep 2009 11:01:15 +0200 [thread overview]
Message-ID: <c62985530909150201p3d5ca037g232c9456e6436fc@mail.gmail.com> (raw)
In-Reply-To: <1252998994.5506.0.camel@laptop>
2009/9/15, Peter Zijlstra <peterz@infradead•org>:
> On Mon, 2009-09-14 at 20:41 +0200, Frederic Weisbecker wrote:
>> 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?
>
> It does anyway, a little further down the line, so sure.
Ok I'll fix it soon using Steve's idea then.
Thanks.
next prev parent reply other threads:[~2009-09-15 9:01 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
2009-09-14 18:41 ` Frederic Weisbecker
2009-09-15 7:16 ` Peter Zijlstra
2009-09-15 9:01 ` Frédéric Weisbecker [this message]
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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