Subject: Re: [PATCH/RFC v3] perf core: Allow setting up max frame stack depth
 via sysctl
To: Frederic Weisbecker <fweisbec@gmail.com>,
        Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>
References: <20160425162706.GB25218@kernel.org>
 <20160425192229.GC25218@kernel.org>
 <20160425200646.GA23875@ast-mbp.thefacebook.com>
 <20160425201750.GD25218@kernel.org>
 <20160425215947.GA25915@ast-mbp.thefacebook.com>
 <20160425234138.GA16708@kernel.org>
 <20160426000724.GA28705@ast-mbp.thefacebook.com>
 <20160426002928.GB16708@kernel.org> <20160426215806.GA15680@lerouge>
 <20160427125358.GM11033@kernel.org> <20160427160903.GA31971@lerouge>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>,
        Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@kernel.org>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Brendan Gregg <brendan.d.gregg@gmail.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Alexei Starovoitov <ast@kernel.org>, He Kuang <hekuang@huawei.com>,
        Jiri Olsa <jolsa@redhat.com>, Masami Hiramatsu <mhiramat@kernel.org>,
        Milian Wolff <milian.wolff@kdab.com>,
        Namhyung Kim <namhyung@kernel.org>,
        Stephane Eranian <eranian@google.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Vince Weaver <vincent.weaver@maine.edu>,
        Wang Nan <wangnan0@huawei.com>, Zefan Li <lizefan@huawei.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
From: David Ahern <dsahern@gmail.com>
Message-ID: <5720E860.10400@gmail.com>
Date: Wed, 27 Apr 2016 10:27:12 -0600
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On 4/27/16 10:09 AM, Frederic Weisbecker wrote:
>>> I first thought that this should be a tunable per event instead of a global sysctl
>>
>> Yeah, I'll work on that too.
>
> There is no rush though. The sysfs limit will probably be enough for most users. Unless
> someone requested it?
>

I have. I spent time last winter (2015) looking into how to do it. The 
userspace syntax was more of a pain than passing the parameters to the 
kernel side as the intent is to specify N kernel frames and M user frames.