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[198.145.29.99]) by mx.google.com with ESMTPS id g21si2921803pfg.286.2019.04.18.08.46.34 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 18 Apr 2019 08:46:34 -0700 (PDT) Received-SPF: pass (google.com: domain of srs0=+lpg=su=goodmis.org=rostedt@kernel.org designates 198.145.29.99 as permitted sender) client-ip=198.145.29.99; Authentication-Results: mx.google.com; spf=pass (google.com: domain of srs0=+lpg=su=goodmis.org=rostedt@kernel.org designates 198.145.29.99 as permitted sender) smtp.mailfrom="SRS0=+LPG=SU=goodmis.org=rostedt@kernel.org" Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 17C4B217D7; Thu, 18 Apr 2019 15:46:31 +0000 (UTC) Date: Thu, 18 Apr 2019 11:46:29 -0400 From: Steven Rostedt To: Thomas Gleixner 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 Message-ID: <20190418114629.023b63d7@gandalf.local.home> In-Reply-To: References: <20190418084119.056416939@linutronix.de> <20190418084254.999521114@linutronix.de> <20190418105334.5093528d@gandalf.local.home> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit 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 17:43:59 +0200 (CEST) Thomas Gleixner wrote: > 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 :) > There's other places I only test 4 deep, so it should be fine to limit it to 4 then. Thanks! -- Steve