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[2a01:7a0:2:106d:700::1]) by mx.google.com with ESMTPS id x184si1761951wmg.6.2019.04.18.08.44.04 for (version=TLS1_2 cipher=AES128-SHA bits=128/128); Thu, 18 Apr 2019 08:44:04 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of tglx@linutronix.de designates 2a01:7a0:2:106d:700::1 as permitted sender) client-ip=2a01:7a0:2:106d:700::1; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of tglx@linutronix.de designates 2a01:7a0:2:106d:700::1 as permitted sender) smtp.mailfrom=tglx@linutronix.de Received: from pd9ef12d2.dip0.t-ipconnect.de ([217.239.18.210] helo=nanos) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1hH9Cj-0004qZ-CV; Thu, 18 Apr 2019 17:44:01 +0200 Date: Thu, 18 Apr 2019 17:43:59 +0200 (CEST) From: Thomas Gleixner To: Steven Rostedt cc: LKML , Josh Poimboeuf , x86@kernel.org, Andy Lutomirski , Alexander Potapenko , Alexey Dobriyan , Andrew Morton , Pekka Enberg , linux-mm@kvack.org, David Rientjes , Christoph Lameter , Catalin Marinas , Dmitry Vyukov , Andrey Ryabinin , kasan-dev@googlegroups.com, Mike Rapoport , Akinobu Mita , iommu@lists.linux-foundation.org, Robin Murphy , Christoph Hellwig , Marek Szyprowski , Johannes Thumshirn , David Sterba , Chris Mason , Josef Bacik , linux-btrfs@vger.kernel.org, dm-devel@redhat.com, Mike Snitzer , Alasdair Kergon , intel-gfx@lists.freedesktop.org, Joonas Lahtinen , Maarten Lankhorst , dri-devel@lists.freedesktop.org, David Airlie , Jani Nikula , Daniel Vetter , Rodrigo Vivi , linux-arch@vger.kernel.org Subject: Re: [patch V2 21/29] tracing: Use percpu stack trace buffer more intelligently In-Reply-To: <20190418105334.5093528d@gandalf.local.home> Message-ID: References: <20190418084119.056416939@linutronix.de> <20190418084254.999521114@linutronix.de> <20190418105334.5093528d@gandalf.local.home> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, 18 Apr 2019, Steven Rostedt wrote: > On Thu, 18 Apr 2019 10:41:40 +0200 > Thomas Gleixner wrote: > > -static DEFINE_PER_CPU(struct ftrace_stack, ftrace_stack); > > +/* This allows 8 level nesting which is plenty */ > > Can we make this 4 level nesting and increase the size? (I can see us > going more than 64 deep, kernel developers never cease to amaze me ;-) > That's all we need: > > Context: Normal, softirq, irq, NMI > > Is there any other way to nest? Not that I know, but you are the tracer dude :) Thanks, tglx