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Subject: Re: [RFC PATCH] perf, bpf: Retain kernel executable code in memory to
 aid Intel PT tracing
To:     Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc:     Ingo Molnar <mingo@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Andi Kleen <ak@linux.intel.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Jiri Olsa <jolsa@redhat.com>, Song Liu <songliubraving@fb.com>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Alexei Starovoitov <ast@kernel.org>,
        linux-kernel@vger.kernel.org, netdev@vger.kernel.org
References: <20190207111901.2399-1-adrian.hunter@intel.com>
 <20190208232924.bpdjuaqufndigtd4@ast-mbp>
 <85ebb8e5-97a0-801a-8d5f-bc09a72047bb@intel.com>
 <20190211081840.j3vhyp3cffftb6m2@ast-mbp>
From:   Adrian Hunter <adrian.hunter@intel.com>
Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki,
 Business Identity Code: 0357606 - 4, Domiciled in Helsinki
Message-ID: <5ecbd520-b73a-5dca-457d-e00f09bf5a06@intel.com>
Date:   Mon, 11 Feb 2019 10:24:35 +0200
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On 11/02/19 10:18 AM, Alexei Starovoitov wrote:
> On Mon, Feb 11, 2019 at 09:54:01AM +0200, Adrian Hunter wrote:
>>
>> Which is not really a real use-case.
> ..
>>> perf analysis with PT becomes inaccurate and main goal
>>> of retaining accurate instruction info is not achieved.
>>
>> For the majority of real use-cases, yes it is.
> 
> In our fleet not a single server is using Intel PT, yet you're
> proposing to penalize all of them with shrinker-based JIT freeing?

I already responded to that.

> There is no negotiation here.

Apart from Peter and Ingo already having indicated a different approach is
preferred, why not? Shouldn't maintainers provide technical reasons.