netdev - Re: [RFC PATCH] perf, bpf: Retain kernel executable code in memory to aid Intel PT tracing

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Message-ID: <5ecbd520-b73a-5dca-457d-e00f09bf5a06@intel.com>
Date:   Mon, 11 Feb 2019 10:24:35 +0200
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Andi Kleen <ak@...ux.intel.com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...hat.com>, Song Liu <songliubraving@...com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Alexei Starovoitov <ast@...nel.org>,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [RFC PATCH] perf, bpf: Retain kernel executable code in memory to
 aid Intel PT tracing

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.