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: 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 [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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1252953076.2964.156.camel@localhost.localdomain \
--to=srostedt@redhat.com \
--cc=fweisbec@gmail.com \
--cc=hpa@zytor.com \
--cc=jaswinder@kernel.org \
--cc=josh@freedesktop.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-next@vger.kernel.org \
--cc=linux-sparse@vger.kernel.org \
--cc=mingo@elte.hu \
--cc=peterz@infradead.org \
--cc=sfr@canb.auug.org.au \
--cc=sparse@chrisli.org \
--cc=tglx@linutronix.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).